insides vs viscus

insides and viscus both are nouns.

Word	Noun	Adjective	Verb	Adverb
insides	Yes	No	No	No
viscus	Yes	No	No	No

As nouns, viscus is a hypernym of insides; that is, viscus is a word with a broader meaning than insides:

insides: internal organs collectively (especially those in the abdominal cavity)
viscus: a main organ that is situated inside the body

Other hypernyms of insides include internal organ.

insides (noun)	viscus (noun)
internal organs collectively (especially those in the abdominal cavity)	a main organ that is situated inside the body