yob vs plug-ugly

yob and plug-ugly both are nouns.

Word	Noun	Adjective	Verb	Adverb
yob	Yes	No	No	No
plug-ugly	Yes	No	No	No

As nouns, plug-ugly is a hyponym of yob; that is, plug-ugly is a word with a more specific, narrower meaning than yob:

Other hyponyms of yob include bullyboy, muscle, muscleman, skin, skinhead, tough guy.

yob (noun)	plug-ugly (noun)
a cruel and brutal fellow	someone who bullies weaker people