Halo CE A will be multiplayer online using the REACH engine. It will have SOME maps of Halo 1 and 2. You get these when your purchase the game. You do not need Reach to play Halo CE A in multiplayer but if you do have reach you can install the maps and have
them in that game when you play multi.
It's MP is essentially Halo Reach. Some time this month, Halo is getting an update. This update is including CE's Pistol, removal of Bloom on weapons like the DMR and bleed trough on shields. Other changes are:
Modify Armor Lock. • Sticky grenade will not be nullified if you use Armor Lock after being stuck. • Damage received while in Armor Lock is transferred to remaining Armor Ability energy. • How much the damage depletes your Armor Lock energy is configurable.
Modify Active Camo. • Reduce the bonus time the player gets in Active Camo while standing still. • Reduce the overall length of time the player can be in Active Camo.
Remove Sword block. • Disable the ability to block Sword attacks using melee with anything other than another Sword.
Now the anniversary edition will have Reachs MP (with the update already out) and will have exclusive maps on the disc only fr owners the Anniversary Edition. At least for now. They may come out as DLC later. The maps
are remakes of CE (and Halo 2s but I'm not sure) maps.
From what I have heard sometime at the mid or end of september/october, there will be a title update for Halo Reach that will have Beta hoppers that will allow the community to try out the tweaks and changes, provide feedback to improve the tweaks mentioned
by Statik Jack.
Also not all of Reach is going to be modified gameplay wise afterwards, the people that like Reach's gamestyle and gametypes can play Vanilla reach playlists and the people that like and prefer the changes will have a classic playlist with the changes.
So it is a win-win for the Reach fans and the Classic halo fans :) Plus we get to have a say in what needs to be done with classic.