Rejuvenation: Instant cast HOT that lasts a moderate amount of time. This is one of your primary raid heals. With the Tier 8 four piece bonus, you gain an instant tick at the beginning of the rejuv heal, which will make it your second best raid healing tool (after wild growth). With the rejuv idol, it’s your most mana efficient HOT in 3.1. Without either the idol or set bonus, it’s still a great HOT because it’s cheap and you can swiftmend it.Thats from restokin.com and u'll find same at EJ forums.Lifebloom: Instant cast HOT (with a large heal “bloom” at the end). Lasts short amount of time. Not recommended as a raid healing tool. The bloom will almost always be overheal. Some people like to use it, and you will get the mana return, but I don’t really recommend throwing around single lifeblooms as a primary raid heal strategy.
Lifebloom - Spell - World of Warcraft = 28% Basemana - 50%at end = 14% Basemana > less HoT effect but big (mostly overhealed) bloom.
Rejuvenation - Spell - World of Warcraft = 18% Basemana > slightly more mana but longer HoT
Since u get only mana for 1 LB back even if u roll 3 stacks.