spark plug vs electrical device

spark plug and electrical device both are nouns.

Word	Noun	Adjective	Verb	Adverb
spark plug	Yes	No	No	No
electrical device	Yes	No	No	No

As nouns, electrical device is a hypernym of spark plug; that is, electrical device is a word with a broader meaning than spark plug:

spark plug: electrical device that fits into the cylinder head of an internal-combustion engine and ignites the gas by means of an electric spark
electrical device: a device that produces or is powered by electricity

spark plug (noun)	electrical device (noun)
electrical device that fits into the cylinder head of an internal-combustion engine and ignites the gas by means of an electric spark	a device that produces or is powered by electricity