fall over backwards vs bend over backwards

fall over backwards and bend over backwards both are verbs.

Word	Noun	Adjective	Verb	Adverb
fall over backwards	No	No	Yes	No
bend over backwards	No	No	Yes	No

As verbs, fall over backwards and bend over backwards are synonyms defined as:

fall over backwards and bend over backwards: try very hard to please someone

fall over backwards (verb)	bend over backwards (verb)
try very hard to please someone	try very hard to please someone