In general, DDAL rules are the same as those in the books. There are a few changes but the biggest difference is in the available content.
1) Character creation is limited to the PHB + one other source book. This means that some combinations are not permitted in DDAL. Characters can only be created using point buy (not rolled stats) and average hit points are always taken on leveling up.
e.g.
Yuan-ti pureblood hexblade warlock ... since the yuan-ti is from volo's guide to monsters and the hexblade is from xanathars.
A bladesinger must be an elf or a half-elf.
If you play a casting class from Xanathars .. shadow sorcerer or hexblade for example ... they can't use the booming blade or green flame blade cantrips since they come from the sword coast adventurers guide.
You can't use the half-elf variant races from SCAG with class archetypes from Xanathars
... basically the only content available to your character at creation must come from ONLY PHB + 1 source ... it is possible to learn spells from other sources but only if you learn them in the adventures you play.
Which leads to the next constraint
2) Only the hardcover adventures and DDAL approved modules are acceptable for DDAL play. The DM has a fair bit of lattitude with how these play out and managing the roleplaying but they can't add treasure, magic items, or increase the XP rewarded by the module. There is more flexibility in the hardcovers but the DM still can't change the content and remain DDAL legal. A DDAL legal character is one that can, theoretically, be played at any DDAL table at home, a game store, a convention or anywhere else.
3) The third difference is log sheets. Every session a DDAL character plays is logged. This includes the name of the module, the DM and their DCI number, the date, starting and finishing XP, gold, renown, downtime and magic items. Anything special or notable occurring in the module like story awards are also noted.
4) Mundane items that drop in a module or adventure can not be kept by the characters. They are considered unusable. Only the specific treasure listed or items specifically purchased from the PHB by the players can be kept.
If you do all that, then you can run DDAL content at your home table and folks can play the characters anywhere. It can work pretty well for hardcover content. On the other hand, if you like running your own content or throwing in your own encounters and rewards then the adventure and characters won't be legal for AL play. For the current play in AL, other than character creation, the rules and rewards basically follow the same pattern as the PHB and DMG outline so there isn't much difference in actual play.
However, the coming season 8, starting on August 30th has a number of changes to module rewards planned. These address some deficiencies in the fairness of the current system when playing DDAL with a more or less different group of people at every seating. However, there are some strong opinions out there on the effect on the immersiveness of the experience.
A quick summary of the changes (which are more or less published at the back of Xanathars).
- instead of earning XP, players earn advancement checkpoints based more or less on one checkpoint for each hour of play. Levels 1 to 4 require 4 checkpoints to advance to the next level while the other levels require 8
- similarly, characters earn treasure points at the rate of 1 treasure point for every 2 hours up to level 10 and 1 treasure point for every hour afterward. Magic items are acquired by spending treasure points and there is a table listing prices for some items. Instead of one person acquiring a specific magic item at the end of a module (which is the norm in AL), all the players in the module unlock the ability to spend treasure points on the magic item.
- gold is only awarded when you advance a level. The amounts listed in Xanathars are quite low and will cause problems for wizards and others with higher character maintenance costs. Hopefully, they will address some of the issues before going live with the revised system.
- the players do not get to keep anything that is found in the module. This is the other main point of contention. From a character perspective, a lot of the modules offer a gold piece reward to entice the characters to participate in the mission. However, under the new system, the characters don't actually get to keep that gold or other rewards. This is a problem since most modules include rooms with encounters and treasure that were originally placed in the modules to increase the XP and gold rewards. Since characters are awarded advancement points and can not keep any gold from these encounters, there is a very reasonable question about why the player would explore different areas (risking the life of the character) when they will literally receive no reward for either the encounters or the treasure found. The player might as well just focus on achieving the primary goal of the encounter and ignore secondary goals that don't offer any rewards.
(the last point is a bit of meta-gaming ... many folks just like to play D&D and can look past the fact that the format won't allow the character to keep what they find perhaps by just pretending the character does get to keep it but spends it on everyday stuff .. and their savings after leveling up is represented by the gold reward when leveling. On the other hand, some folks who play AL can be quite mercenary and the "LOOTZ" that their character actually receives is very important to them. For these folks, this change substantially impacts why the PLAYER wants to play. AL has a wide variety of people with different interests and reasons to play ... and any particular random table can have seven players with very different motivations and interests so it can be challenging coming up with a system that keeps everyone happy).
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As an example of the kind of play that the new system is trying to address. The current AL magic item system is designed to try to fairly distribute magic items. When you play a module, the first choice for the magic item that drops (there is usually only one) goes to the character with the fewest magic items. If they don't want it then the characters with the next fewest and so on. If more than one character with the same number of magic items would like the current item then a dice roll is made to randomly determine who receives it.
This system is actually pretty good but it is broken in a few ways.
1) Modules can be played with anywhere from 3 to 7 players. Obviously, your chance of getting the magic item is much higher if you play in a group of 3 than one of 7.
2) Tier 1 goes from level 1-4 ... characters typically start off with no magic items. This means that by level 4 the chances of receiving the magic item in a tier 1 adventure drop alot since there are often lower level players without magic items.
3) Magic items can be traded. Many players prefer to take items that their current character can use. On the other hand, other players will roll on any item that drops (if they have a lower count of magic items) particularly if it is an item that might be in high demand. They do this so they can trade it for something they might actually want. However, other players in the game might well have been able to use the item for the character in the game itself and may not have easy access to trading. Some players can find this situation very frustrating because some items that might be very useful for a particular class might only drop in a limited number of modules (only one in some cases ... and the only way to get it if you don't receive it in the module is by trading). This fundamental conflict and frustration found by some players is probably one of the bigger motivators behind the treasure point system. Any magic item that drops in a module that character has played is potentially something you can buy.
4) "Griefing". Imagine a game store with a reasonable number of different players. They come each week, sign up to play a module, have some fun and maybe walk away with some treasure. Now picture another player whose enjoyment mostly comes from the magic item that can be obtained at the end. They love walking out having won the magic item whether the character can use it or not. They bring a level 1 character and play it until it wins a magic item then they create a new level 1 and do the same the following week. The problem is that even with a relatively large group of tier 1 players, most of the tier 1s will level up and acquire magic items. After a while, the odds are good that this one player will receive the magic items from most modules played to the frustration of the other players at the table. It is completely fair under AL rules and who is to say what should be fun for each player. The new system tries to avoid this sort of situation as well.
