ground level vs ground floor

ground level and ground floor both are nouns.

Word	Noun	Adjective	Verb	Adverb
ground level	Yes	No	No	No
ground floor	Yes	No	No	No

As nouns, ground level and ground floor are synonyms defined as:

ground level and ground floor: the floor of a building that is at or nearest to the level of the ground around the building

Other synonyms of ground level include first floor.

ground level (noun)	ground floor (noun)
the floor of a building that is at or nearest to the level of the ground around the building	the floor of a building that is at or nearest to the level of the ground around the building
the height of the ground on which something stands	becoming part of a venture at the beginning (regarded as position of advantage)