fiddleneck vs scorpion weed

fiddleneck and scorpion weed both are nouns.

Word	Noun	Adjective	Verb	Adverb
fiddleneck	Yes	No	No	No
scorpion weed	Yes	No	No	No

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

fiddleneck: hairy annual of California to Mexico with crowded cymes of small blue to lilac or mauve flowers
scorpion weed: any plant of the genus Phacelia

Other hypernyms of fiddleneck include phacelia, scorpionweed.

fiddleneck (noun)	scorpion weed (noun)
hairy annual of California to Mexico with crowded cymes of small blue to lilac or mauve flowers	any plant of the genus Phacelia