data file vs mug file

data file and mug file both are nouns.

Word	Noun	Adjective	Verb	Adverb
data file	Yes	No	No	No
mug file	Yes	No	No	No

As nouns, mug file is a hyponym of data file; that is, mug file is a word with a more specific, narrower meaning than data file:

data file: a set of related records (either written or electronic) kept together
mug file: a file of mug shots (pictures of criminals that are kept on file by the police)

Other hyponyms of data file include computer file, mug book, tickler, tickler file, editorial file.

data file (noun)	mug file (noun)
a set of related records (either written or electronic) kept together	a file of mug shots (pictures of criminals that are kept on file by the police)