The word protection or impeccability may be used of both prophets and angels, but their scope and objects differ. Prophets transmit revelation and guide human communities. Angels perform the tasks and services assigned by God.
An argument protecting a prophet's delivery of revelation cannot simply be transferred verbatim to every possible angelic situation. Nor does the Qur'anic description of angelic obedience by itself establish that angels outrank prophets.
Protection from sin and comparative excellence are different properties requiring their own proofs.