No. A fireball never heals the party. A fireball can only contribute to ending an encounter, outside of things like burning down the only way into a saferoom.So you would agree that fireball can heal the party but doesn’t always do so?
A Rope Trick, on the other hand, allows you a short rest. Not allows you to start taking, like ending an encounter with a fireball will, it guarantees you the hour needed to complete a short rest.