filename vs file name

filename and file name both are nouns.

Word	Noun	Adjective	Verb	Adverb
filename	Yes	No	No	No
file name	Yes	No	No	No

As nouns, filename and file name are synonyms defined as:

filename and file name: (computer science) the name given to a computer file in order to distinguish it from other files; may contain an extension that indicates the type of file

Other synonyms of filename include computer file name, computer filename.

filename (noun)	file name (noun)
(computer science) the name given to a computer file in order to distinguish it from other files; may contain an extension that indicates the type of file	(computer science) the name given to a computer file in order to distinguish it from other files; may contain an extension that indicates the type of file