hotdog vs red hot

hotdog and red hot both are nouns.

Word	Noun	Adjective	Verb	Adverb
hotdog	Yes	No	No	No
red hot	Yes	No	No	No

As nouns, hotdog and red hot are synonyms defined as:

Other synonyms of hotdog include hot dog.

hotdog (noun)	red hot (noun)
a smooth-textured sausage of minced beef or pork usually smoked; often served on a bread roll	a frankfurter served hot on a bun
a frankfurter served hot on a bun
someone who performs dangerous stunts to attract attention to himself