EE
Healer, gets greater heal
Has sleep, but not root
Fast cast speed
Lacks offensive buffs, doesn't increase damage output of party, increases defense
High level rez
Party recall (neat skill, instant return party to town - many uses, especially in pvp)
Can recharge MP
Cannot cure paralysis
Will get trance in C5 (fast, short-lasting, easy-landing sleep)
Has undead nuke
Usually considered a bit gimped. Considered a great PvP healer.
SE
Buffer/healer hybrid, gets greater heal and greater group heal
...but also offers a lot of offensive buffs, including crit related buffs, and empower that all nukers love
Has root but not sleep
Slow cast speed
Low level rez (20%, stops learning at level 35)
Can recharge MP
Will not get trance in C5
Can cure paralysis
Doesn't have undead nuke
Usually considered the most versatile support class, fits most situations and does it rather good too. Basically the only support class that is good at both buffing and healing.
Bishop
Pure healer, gets greater heal, greater group heal AND greater quick heal and at higher intensity than EE and SE, also gets % heal for heal sponges (and griefing purposes)
Has sleep, but not root
Medium cast speed
Lacks buffs in general but has a few good ones towards increasing healing efficiency
Highest level rez
Can mass/aoe rez (very good range with C5 changes)
Cannot recharge MP
Can cure paralysis (right?)
Will get trance in C5
Has undead nuke
Usually considered the best pure healer.
Prophet
Pure buffer, has no heals really (but the heals from level 35 still works if healing isn't strained)
Has root, but not sleep
Medium cast speed
Basically has most of the offensive buffs you need, however two of the unique are available in pots these days
Low level rez (20%, stops learning at level 35)
Cannot recharge MP
Has self recall, to instantly return him/herself to town = hard to die
Cannot cure paralysis
Doesnt have undead nuke
Will not get trance in C5
Has heavy armor masteries, the others only get robes and light.
Usually considered the best buffer, alongside the Warcryer that shares most of the same offensive buffs (though warcryer gets vamp rage, but not wind walk, for instance). Also see the term Battle Prophet in the forum search. When considering a buffer, also consider the Warcryer who has a lot more damage potential (actually has offensive skills and spells).
Have slowest cast speed. Decent heals. recharge and a mix of the good buffs. Their speciality buff empower (+66% m atk or so)is a necessary for all nukers making them a nuker duoer mainly, but they can find large parties with their heals and Vampric Rage buff (regen HP based on dmg u do to a mob)
EE.
Fastest heals/recharges in the game, while the EE has mana expect yourself to be almost invicible to anything less that 6 players or 15 mobs hitting you. Basic healer buffs including great defensive buffs especially with a shield. Lacking emp, nukers don't duo with it much now but in C5 with the specific buff (clarity -12% mp cost) they will get more duos. This class doesn't have purify (cure paralyse) so some grouping area's will have to be avoided. Can Save their party with a quick spell (party return) which instantly returns all party members to town.
Bishop is a healer, gets 1-2 buffs after lvl 40, but got most different heals in game and highest res. Profet got the most buffs in game and doesnt gets new heals after lvl 35, also got a low % res.
Sword Muse
Song of Meditation - Increase MP recovery.
Song of Renewal - Decrease MP use of skills
Song of Champion - Decrease MP use of styles
Elemental Summoner
xxx of Seraphim (I play one and can't remember!) - Increase MP regeneration, 3 levels available depending on the level of the servitor
Elven Elder (C5 Only)
Clarity - Reduce the cost of spells.