Again, I am not sure what this "encounter-based design" really means.
Encounter-based design means that the tone of adventure writing is built around the "encounter". If a good portion of the party's resources reset after a short 5-10 minute rest, then that is going to be and encounter-based design. A daily-based design means that the adventure is written around the "adventuring day". If a good portion of the party's resources reset after a long rest of 8 hours, it's daily-based.
The reason the entire design of adventures shift is because there is no real loss of resources from one encounter to the next in encounter-based design. You get all your encounter powers back and you can spend a healing surge or two to get back to full HP. After that 5 minute rest, you are back exactly to the point you were before the fight started. This means that the encounter itself has no real lasting impact on the game day.
D&D 4e did have some daily resources. Daily powers, obviously. There was also healing surges and, before the rules update, magic item power uses. Other than expending those, the party was back to complete and full strength after each encounter.
What this means for designing an adventure was that each individual encounter had to be challenging in and of itself. If an encounter doesn't threaten the party in some way, it's not going to be challenging because they can waltz right through it without expending any useful resources. They have no reason to hold back encounter powers, for example, if there's only one or two enemies. They'll use an encounter power, use an action point (which is reset after every two encounters so it's still encounter-based), and use another one if they're 3rd level or higher. Since encounter powers are twice as effective typically than at-will powers (doing twice as much damage or affecting an area), they will pretty much always win these kinds of encounters.
Alternately, larger or more difficult encounters can become very threatening in this sort of game. The players will typically only have a few encounter powers (1 at 1st, 2 at 3rd, 3 at 7th, etc.). Those resources can't be horded, so they can't hold one back from Encounter 1 and then use it twice in Encounter 2 since they're reset at the end of the encounter. They walked into the far more dangerous encounter with the exact same resources they had in the previous, easier encounter.
For example, if the party comes across a pair of guards 30 feet away in front of a goblin cave, it's almost pointless to waste the time rolling initiative or setting up the board. If they win initiative, they're going to rush up and use their stronger encounter powers to kill them both before they get a turn. If they lose initiative, and one of the goblins gets to attack, no big deal. It's just a few HP, the goblin's probably going to die before it gets a turn again, and the player that was hit can use a healing surge (one of 6 to 10 per day, so very little loss of resource) to get back the HP.
If, however, the goblins have a chance to call for reinforcements of a dozen warriors, which is now a sizable advantage to the goblins. The players don't have enough encounter powers to drop them all quickly and the encounter has just become far more dangerous to the point of possibly being unwinnable.
Daily-based design, on the other hand, focuses on the adventuring day. Such small encounters
do cause resources to be used like hit points, spells, etc. Even with a mechanic like hit dice to regain HP, it's still a great loss of resources - you use one of up to 3 HD you have (at 3rd level, since you seem to get one per level) to gain back some HP. That's a big resource. If you have a power or ability you can do 3 times per day and have to use one, that's 1/3 of that resource.
Because of that style of design, adventures can be written with more variety. To take the example from above, the players won't necessarily automatically win against the two goblin guards, even if they do win initiative. If they survive the first hit or win initiative, they can attack back, costing the characters a small amount of HP which may make them choose between staying at lower HP or using a HD after the encounter.
If the goblins raise an alarm and a dozen goblins pour out of the cave, the party still has a wealth of resources to throw at the encounter. They can start using their spells and X times per day abilities one after another to thin the group out and regain HP that are lost. It may be a challenge and they may expend all their daily resources (forcing them to retreat and rest), but it is not the complete table turning from easy encounter to TPK it is with the other system.
The reason why most of us feel that daily-based design is better than encounter-based design (or at least I feel this way) is that you can design an adventure that is encounter-based in a system that has daily-based resources. I can craft my encounters so that each one is challenging in and of itself without being overwhelming, forcing the characters to use their resources at a regular pace. Or I can go to either extreme, having a larger number of smaller encounters that slowly whittle away their resources, or one single huge encounter that uses them all in one big fight.
If you have encounter-based resources (again, I'm talking about the vast majority of the resources refreshing after each encounter), you can only create adventures in the encounter-based design without doing a lot of hard work and most likely adding in several house rules redefining exactly what an encounter is. There is no whittling down of resources like above because the resources refresh after each encounter - nothing is lost. You also can't have one single massive blow-out encounter because the players do not have the overwhelming resources they have in the other system - they have the same resources they have for every other encounter (plus possibly a daily power or two).
Did that explain it a little bit better?
