short pants vs shorts

short pants and shorts both are nouns.

Word	Noun	Adjective	Verb	Adverb
short pants	Yes	No	No	No
shorts	Yes	No	No	No

As nouns, short pants and shorts are synonyms defined as:

short pants and shorts: (used in the plural) trousers that end at or above the knee

Other synonyms of short pants include trunks.

short pants (noun)	shorts (noun)
(used in the plural) trousers that end at or above the knee	(used in the plural) trousers that end at or above the knee
	underpants worn by men