A faqīh is not simply someone who memorizes terms. The important feature is sound understanding of religious rulings and their correct application. Such understanding helps recognize misleading ideas and guide people toward what is right.
An ʿābid is a worshipper. The comparison does not belittle worship; it highlights the distinctive benefit of knowledge that helps keep both worship and conduct sound.
For example, a sincere person may misunderstand how to carry out a good deed. Someone who understands the relevant teaching can explain it accurately and respectfully.