Planck's constant vs h

Planck's constant and h both are nouns.

Word	Noun	Adjective	Verb	Adverb
Planck's constant	Yes	No	No	No
h	Yes	No	No	No

As nouns, Planck's constant and h are synonyms defined as:

Planck's constant and h: the constant of proportionality relating the energy of a photon to its frequency; approximately 6.626 x 10^-34 joule-second

Planck's constant (noun)	h (noun)
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
	the constant of proportionality relating the energy of a photon to its frequency; approximately 6.626 x 10^-34 joule-second