insides vs viscera

insides and viscera both are nouns.

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

As nouns, insides and viscera are synonyms defined as:

insides and viscera: internal organs collectively (especially those in the abdominal cavity)

Other synonyms of insides include entrails, innards.

insides (noun)	viscera (noun)
internal organs collectively (especially those in the abdominal cavity)	internal organs collectively (especially those in the abdominal cavity)