ASSUME: To authenticate by means of belief; to surmise; to suppose to be true, especially without proof.

PRESUME: To perform, do (something) without authority; to lay claim to without permission.

Vocabulary.com meanwhile asserts that, Assume and Presume both mean to believe something before it happens, but when you assume you're not really sure.

Can the gurus and the tacticians in English language in this forum put more light to this scenario please.

Mr. Mods please do the needful FP things, thanks.