Education is painful

So, I've learned two very important things today, the first is that I'm not twenty anymore, and can no longer teach grappling right after lifting weights..or is that I can't lift weights just before I hold a grappling class (either way my back hurts and I'm not happy).
But I've also learned there were some big mechanical differences between original d&d and the Moldvay set. You see last night I decided to buy the pdf of Micheal "Chgowiz" Shortens Swords and Wizardy's Reference Sheets. Well I was very pleased with the product, I felt it gave concise information in a useful format, and even gave intstructions on how to make a booklet form of the sheets (I guess I learned something new about my printer too). However when I crossed referenced the mechanic info on levels, spell progression, and turning values ( heck even item prices) I was struck with how much diference there was between oD&D and B/X D&D. I mean I should have been aware of the fact that there would be some differences yes, but I hadn't realized the extent. As a quick example take the cleric (please....ohh groan); in swords and wizardry ( and by extension oD&D I'm assuming) a 10th level cleric requires 225,000 exp, as opposed to B/X which requires 300,000. In swords and Wizardry the spells at 10th level are 3,3,3,3,3; while in B/X its 4,4,3,3,2; the same with turning in B/X they can destroy a vampire (I'm not sure I like this as a smart vampire makes a good NPC foe you just don't want to be obliterated so easily, in Swords and Wizardry ( and again by extension oD&D) you don't have this problem as they can only be TURNED on a 10 (on a d20 of course). This is only one example. Again I knew the mechanics were not exactly the same but I'm still surprised to see just how different they are. A general trend would show that characters progressed faster in terms of exp points in oD&D, maybe not time wise as it may have been harder to earn said experience points in the first place, while B/X D&D had slower progressions with more powerful changes at each new level. I wonder why that was?
Well any way the reference sheets are still good for me, but not quite as usefulr for my game as I thought, because Its going to be a combined Moldvay/Mentzer D&D game (I just hope these two aren't different mechanically.
Maybe I can find a way to create my own sheets...ummm food for thought.