standard pressure vs atm

standard pressure and atm both are nouns.

Word	Noun	Adjective	Verb	Adverb
standard pressure	Yes	No	No	No
atm	Yes	No	No	No

As nouns, standard pressure and atm are synonyms defined as:

standard pressure and atm: a unit of pressure: the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade

Other synonyms of standard pressure include atmosphere, standard atmosphere.

standard pressure (noun)	atm (noun)
a unit of pressure: the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade	a unit of pressure: the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade