Sat vs Saturday

Sat and Saturday both are nouns.

Word	Noun	Adjective	Verb	Adverb
Sat	Yes	No	No	No
Saturday	Yes	No	No	No

As nouns, Sat and Saturday are synonyms defined as:

Sat and Saturday: the seventh and last day of the week; observed as the Sabbath by Jews and some Christians

Other synonyms of Sat include Sabbatum.

Sat (noun)	Saturday (noun)
the seventh and last day of the week; observed as the Sabbath by Jews and some Christians	the seventh and last day of the week; observed as the Sabbath by Jews and some Christians