baptism vs immersion

baptism and immersion both are nouns.

Word	Noun	Adjective	Verb	Adverb
baptism	Yes	No	No	No
immersion	Yes	No	No	No

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

baptism: a Christian sacrament signifying spiritual cleansing and rebirth
immersion: a form of baptism in which part or all of a person's body is submerged

Other hyponyms of baptism include affusion, aspersion, sprinkling, christening.

baptism (noun)	immersion (noun)
a Christian sacrament signifying spiritual cleansing and rebirth	a form of baptism in which part or all of a person's body is submerged
	the act of wetting something by submerging it
	complete attention; intense mental effort
	sinking until covered completely with water
	(astronomy) the disappearance of a celestial body prior to an eclipse