A very basic Basic question

[Mouseferatu]

I've actually got the chance to play in an upcoming BECMI campaign , and I realized that my familiarity is strictly with the Moldvay set. Am I correct in my belief/understanding that the differences between the Moldvay and Mentzer sets are primarily differences of presentation, and that the actual mechanics and rules are pretty near identical?

 

[Serendipity]

Yes, the few differences are very minor - if memory serves the biggest difference between the two was initiative but I don't recall what the differences were. (Actually on some reflection, the advancements for clerics and I think thieves were a bit different in the respective Expert sets but that shouldn't come up early.) If you're familiar with Moldvay you should be set.

 

[Iosue]

Initiative is exactly the same. Side initiative, d6, high roll wins. If you're just playing BE of BECMI, gameplay-wise it's virtually exactly the same as B/X. Most of the differences are in character advancement (different progression for thieves' abilities and cleric spells, magic-users start with Read Magic in their spellbook in the BECMI rules).

 

[Voadam]

BECMI also reduces the thief's thief abilities. The thief in BX expert levels is about as competent as a BECMI thief in the companion levels.

Because you know the thieves were just overpowered with being competent at their class abilities in the expert range.

BECMI in addition introduces the mechanics of weapon mastery and the noncombat system similar to non weapon proficiencies. I think those are explained in the Master set.

 

[Serendipity]

Initiative is exactly the same.

Indeed. I was probably thinking of the differences between Holmes and Moldvay; having since checked, initiative is uncharged from Moldvay through the Rules Cyclopedia, which collect the BECMI rules through the masters set.
Otherwise, clerics advance at the same rate but their spell progression is less generous in Mentzer starting around level 6. Conversely, thief xp advancement (again) is the same in both, but the advancement of their thieving abilities is very different.
This should teach me to check first before posting, especially when tired.

 

[Ashtagon]

Weapon mastery is introduced in BECMI

Fighters get high level "prestige classes" to choose from.

Mass combat, dominion, artifact, and immortality quest rules are introduced in BECMI.

Thieves get their abilities weakened

Elves have a different spell progression (B?X ends up with more 1st level and fewer 5th than BECMI).

 

[MerricB]

The differences between Moldvay Basic and Mentzer Basic are very small. The major changes come between the Expert sets, as Mentzer was designing more for levels up to 36, and so slowed down the quickness abilities were gained during the expert levels of the Moldvay/Cook set.

Cheers!