roughneck vs tough guy

roughneck and tough guy both are nouns.

Word	Noun	Adjective	Verb	Adverb
roughneck	Yes	No	No	No
tough guy	Yes	No	No	No

As nouns, tough guy is a hyponym of roughneck; that is, tough guy is a word with a more specific, narrower meaning than roughneck:

Other hyponyms of roughneck include bullyboy, muscle, muscleman, skin, skinhead, plug-ugly.

roughneck (noun)	tough guy (noun)
a cruel and brutal fellow	someone who bullies weaker people