H vs h

H and h both are nouns.

Word	Noun	Adjective	Verb	Adverb
H	Yes	No	No	No
h	Yes	No	No	No

As nouns, H and h are synonyms defined as:

H (noun)	h (noun)
(thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure	the 8th letter of the Roman alphabet
the 8th letter of the Roman alphabet	the constant of proportionality relating the energy of a photon to its frequency; approximately 6.626 x 10^-34 joule-second
a unit of inductance in which an induced electromotive force of one volt is produced when the current is varied at the rate of one ampere per second
a nonmetallic univalent element that is normally a colorless and odorless highly flammable diatomic gas; the simplest and lightest and most abundant element in the universe