whip scorpion vs arachnid

whip scorpion and arachnid both are nouns.

Word	Noun	Adjective	Verb	Adverb
whip scorpion	Yes	No	No	No
arachnid	Yes	No	No	No

As nouns, arachnid is a hypernym of whip scorpion; that is, arachnid is a word with a broader meaning than whip scorpion:

whip scorpion: nonvenomous arachnid that resembles a scorpion and that has a long thin tail without a stinger
arachnid: air-breathing arthropods characterized by simple eyes and four pairs of legs

Other hypernyms of whip scorpion include arachnoid.

whip scorpion (noun)	arachnid (noun)
nonvenomous arachnid that resembles a scorpion and that has a long thin tail without a stinger	air-breathing arthropods characterized by simple eyes and four pairs of legs