false scorpion vs arachnid

false scorpion and arachnid both are nouns.

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

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

false scorpion: small nonvenomous arachnid resembling a tailless scorpion
arachnid: air-breathing arthropods characterized by simple eyes and four pairs of legs

Other hypernyms of false scorpion include arachnoid.

false scorpion (noun)	arachnid (noun)
small nonvenomous arachnid resembling a tailless scorpion	air-breathing arthropods characterized by simple eyes and four pairs of legs