low gear vs first gear

low gear and first gear both are nouns.

Word	Noun	Adjective	Verb	Adverb
low gear	Yes	No	No	No
first gear	Yes	No	No	No

As nouns, low gear and first gear are synonyms defined as:

low gear and first gear: the lowest forward gear ratio in the gear box of a motor vehicle; used to start a car moving

Other synonyms of low gear include first, low.

low gear (noun)	first gear (noun)
the lowest forward gear ratio in the gear box of a motor vehicle; used to start a car moving	the lowest forward gear ratio in the gear box of a motor vehicle; used to start a car moving