underperform vs underachieve

underperform and underachieve both are verbs.

Word	Noun	Adjective	Verb	Adverb
underperform	No	No	Yes	No
underachieve	No	No	Yes	No

As verbs, underperform and underachieve are synonyms defined as:

underperform and underachieve: perform less well or with less success than expected

underperform (verb)	underachieve (verb)
perform too rarely	perform less well or with less success than expected
perform less well or with less success than expected