Oh boy, this again. (Not directed at you OP) Please don't let this become another WHM vs. SCH war thread.

In general, WHM has easier AoE heals with Regen/Medica II and is more of a reactive healer with the ability to repair spike damage in one or two casts. SCH is more focused on damage mitigation (preemptive healer) with shields like Adloquium/Succor and Sacred Soil (10% less damage received). SCH also has fewer problems with enmity generation and MP due to Aetherflow and a lot of the heals coming from fairies. Both have their pros and cons so not going to get into the whole "which is better" business.

I personally find SCH to be more difficult to play because you have far more tools at your disposal, but I also find SCH more fun and rewarding to play because there's more action involved. I switch between the two freely because I feel certain content is way easier as one or the other (e.g. WHM for CT because Medica II makes King Behemoth's lightning field a joke, SCH for Titan HM because Sacred Soil and MP for raises if needed) ... it may also be because I haven't fully mastered SCH yet. >.>