remain firm vs withstand

remain firm and withstand both are verbs.

Word	Noun	Adjective	Verb	Adverb
remain firm	No	No	Yes	No
withstand	No	No	Yes	No

As verbs, withstand is a hypernym of remain firm; that is, withstand is a word with a broader meaning than remain firm:

remain firm: hold one's ground; maintain a position; be steadfast or upright
withstand: stand up or offer resistance to somebody or something

Other hypernyms of remain firm include hold out, resist, stand firm.

remain firm (verb)	withstand (verb)
hold one's ground; maintain a position; be steadfast or upright	stand up or offer resistance to somebody or something
	resist or confront with resistance