proton vs hydrogen ion

proton and hydrogen ion both are nouns.

Word	Noun	Adjective	Verb	Adverb
proton	Yes	No	No	No
hydrogen ion	Yes	No	No	No

As nouns, hydrogen ion is a hyponym of proton; that is, hydrogen ion is a word with a more specific, narrower meaning than proton:

proton: a stable particle with positive charge equal to the negative charge of an electron
hydrogen ion: a positively charged atom of hydrogen; that is to say, a normal hydrogen atomic nucleus

proton (noun)	hydrogen ion (noun)
a stable particle with positive charge equal to the negative charge of an electron	a positively charged atom of hydrogen; that is to say, a normal hydrogen atomic nucleus