Originally Posted by DadofTwins

I assume you're referencing NFHS here?

Judgment call. Basically, if a keeper controls the ball with his hands (catch and drop, directed punch, etc.), once it goes to the ground he can't pick it up again. The FIFA wording is "releas(ing) it from his possession."

Whether the keeper had control/possession (parried) or not (deflected) is "in the opinion of the referee."