transformer vs coil

transformer and coil both are nouns.

Word	Noun	Adjective	Verb	Adverb
transformer	Yes	No	No	No
coil	Yes	No	Yes	No

As nouns, coil is a hyponym of transformer; that is, coil is a word with a more specific, narrower meaning than transformer:

transformer: an electrical device by which alternating current of one voltage is changed to another voltage
coil: a transformer that supplies high voltage to spark plugs in a gasoline engine

Other hyponyms of transformer include step-down transformer, step-up transformer, Tesla coil, voltage regulator.

transformer (noun)	coil (noun)
an electrical device by which alternating current of one voltage is changed to another voltage	a structure consisting of something wound in a continuous series of loops
	reactor consisting of a spiral of insulated wire that introduces inductance into a circuit
	tubing that is wound in a spiral
	a contraceptive device placed inside a woman's womb
	a transformer that supplies high voltage to spark plugs in a gasoline engine
	a round shape formed by a series of concentric circles (as formed by leaves or flower petals)

transformer (verb)	coil (verb)
	wind around something in coils or loops
	make without a potter's wheel
	to wind or move in a spiral course