Unless they have changed it.. the xp from being in a raid is less then a party.. allways been like that... And there is many things you cant enter as a raid.. Like 5mans and AV you will get a mesage "you are not abligated to enter this while beeing in a raid group." i dont know.. maybe they have change that reasently.. but i know that last week i needed to quite raid and remake a party yo enter an heroic.. and also when i was doing AV...
I also remeber that i had some trubble while questing when i was in a raid but i cant really recal exact what that was...