100 mL vs double shot

100 mL and double shot both are nouns.

Word	Noun	Adjective	Verb	Adverb
100 mL	Yes	No	No	No
double shot	Yes	No	No	No

As nouns, 100 mL and double shot are synonyms defined as:

100 mL (noun)	double shot (noun)
100 mL of liquor, drunk from a shot glass.	100 mL of liquor, drunk from a shot glass.