insect vs arthropod

insect and arthropod both are nouns.

Word	Noun	Adjective	Verb	Adverb
insect	Yes	No	No	No
arthropod	Yes	No	No	No

As nouns, arthropod is a hypernym of insect; that is, arthropod is a word with a broader meaning than insect:

insect: small air-breathing arthropod
arthropod: invertebrate having jointed limbs and a segmented body with an exoskeleton made of chitin

insect (noun)	arthropod (noun)
small air-breathing arthropod	invertebrate having jointed limbs and a segmented body with an exoskeleton made of chitin
a person who has a nasty or unethical character undeserving of respect