Commenting on the extra badges/points that are to be gained from 25m raidings vs 10m raiding (source
GHOSTCRAWLER: We're still messing around with the numbers because we want a system that works not only at launch but once there are multiple raid tiers and perhaps weekly raid quests and the whole nine yards. A very general idea (meaning it could end up being different) is that a group that can clear a 25-player raid can earn all of their points that way, while a 10-player group may need to supplement that income with more Dungeon Finder runs. We also recognize that badges are attractive early in a tier but that they lose their luster once you've earned a few pieces, so they can't be the only incentive.
Confirming if the boss kill achievements will be different for 25 and 10 man raiding (source
GHOSTCRAWLER: Single achievement.