Spells and Abilities have different purposes. Spells are always ready to be used while an Ability can only be used once every so often. In exchange Healing Abilities are typically very powerful and Healing Spells somewhat weak in comparison. Abilities don't need to be buffed because they are already designed to save you in a tough spot. Healing Spells are used to handle normal damage and you buff these Spells when the damage to the party is slightly heavier than normal. Your last resort is a Special Healing Ability. Learning the difference and proper usage of all these techniques is what makes being a healer fun and gives you room to grow in skill and mastery as you progress.