odd man out vs odd fellow

odd man out and odd fellow both are nouns.

Word	Noun	Adjective	Verb	Adverb
odd man out	Yes	No	No	No
odd fellow	Yes	No	No	No

As nouns, odd man out and odd fellow are synonyms defined as:

odd man out and odd fellow: someone regarded as eccentric or crazy and standing out from a group

Other synonyms of odd man out include kook, odd fish, queer bird, queer duck.

odd man out (noun)	odd fellow (noun)
someone regarded as eccentric or crazy and standing out from a group	someone regarded as eccentric or crazy and standing out from a group