Now we move on to the meat of the matter: the classes. This post will deal with the "Core Three / Four".
Original Dungeons & Dragons:
Here we have three classes (although many see the Thief as "core" it wasn't initially. That being said, we will use Supplement I to cover the Thief class). Fighting-Men, Magic-Users and Clerics. Then we have Dwarves (Fighting Men), Elves (Fighting Men and Magic-users) and Halflings (piss poor Fighting Men). Organization of the presentation of the classes is piss poor, but that is part and parcel of the OD&D presentation of classes. Some call it charm. I call it something that the clones definitely got right.
Fighting-Men - Can use all magical weaponry. More hit dice.
Magic-Users - Can use "a whole plethora of enchanted items". Wizards (11th level) and above may create magic items. Spells obviously
Clerics - Can use magic armor and all non-edged magic weapons and can cast Cleric Spells as well as Turn Undead. At 7th level must declare for either Law or Chaos
Thieves (Greyhawk Supplement) - Thief skills increase per level as a percentage, except for Hear Noise, which is bases on a d6.
The Fighter - Can use the majority of magic weaponry, withstands more damage, against enemies 1+1 HD or less gains 1 attack per level.
The Magic-user - Greatest selection of enchanted items. At 9th level can enchant items of his own. and of course spells
The Cleric - Must choose law or chaos. Can use armor and shields, but edged and piercing weapons are prohibited. At 2nd level gains a spell book of first level spells. (WTF?). Turn undead.
The Thief (optional class) - thief skills succeed on a 3-6 on a D6 - no matter the level. Can read magic-user spells scrolls at 9th level. Backstab is +4 hit, with 2 dice of damage for every 4 levels or fraction thereof.
Swords & Wizardry WhiteBox:
The Fighter - Can use all weapons and armor. Against foes 1 HD or lower, 1 attack per level.
The Magic-user - No mention of creating magic items.
The Cleric - Blunt weapons and any armor. Spells. Turn Undead
The Thief - ain't got none ;)
So, my observations:
Delving Deeper makes a claim that it keeps closer to the original, but I don't see it just yet. Since when did Clerics have Spell Books? (since page 34 apparently)
I've heard it mentioned that the DD Thief class is based on so "proto" version before the published version in Greyhawk. Whatever, it's not based on a published version - the one that EGG presented. It doesn't feel "right". If you are going to make the argument that you are closer to the original than other clones, why stray so far?
Both DD and S&W WB have fighters getting multiple attacks against 1HD creatures. I remember that from AD&D, I haven't found it yet in the OD&D set, but God himself knows where it might be buried ;)