Cast healing is the default, using a book and later on armor sets for ressource generation, you keep your group alive with a combination of HoT-abilities and fast castable direct heals.
The main point in the related build is getting the aoe-detaunt tactic of the wrath-mastery, that allows you to keep healing unter pressure, where other healing classes would need to run and stop healing.
Havin that tactic, most choose to go for the group-cleanse tactic(Cleansing Power) in the salvation tree, picking up both divine light and pious restoration on their way.
The related renown spec is usually meant to make you as tanky as possible, normally choosing trivial blows as a basis in rvr-t4/sc-t3 and adding in other defensive renown abilities or stats with the other points.
Hardy Concession, Deft Defender and Reflexes are ususal picks. The last two also help increasing the proc-rate of Exalted Defences, a major increase in healing done.
Willpower is usually way to ineffective in higher tiers, because the amount gained by gear is sufficient.
Melee specs, no matter if trying to melee heal or playing for maximised damage, are rather similar, since both specs are reliant on the damage done to enemies.
At the time of writing this article, all melee-specs are way less effective then a pure cast-healing spec in groupplay.
These are normally similar, both combine the wrath and the grace tree for highest possible damage in melee.
Actual melee-healers will take Grace of Sigmar as a tactic, increasing their healoutput by a major amount, while most dps-warrior priests will rather increase the wrath tree as much as possible to get the highest returns from Hammer of Sigmar.
Both specs usually take fanaticism and divine wrath as tactics, since neither spec has much use for casted heals, stacking stats for both is normally not possible.
For renown, trivial blows is a must have in rvr-t4/sc-t3, as with about any other class. To deal with enemy armor, weaponskill is the most relevant stat afterwards, since there is enough strenght on most higher level gear.
Melee-crit or additional strength are especially favourite among the dps-warrior priests, who gain a higher burst by it, while the melee healers will often choose some defence like parry or toughness instead.