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)
the 8th letter of the Roman alphabet	(thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure
the constant of proportionality relating the energy of a photon to its frequency; approximately 6.626 x 10^-34 joule-second	the 8th letter of the Roman alphabet
	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