beforehand vs ahead

beforehand and ahead both are adjectives.

Word	Noun	Adjective	Verb	Adverb
beforehand	No	Yes	No	Yes
ahead	No	Yes	No	Yes

As adverbs, beforehand and ahead are synonyms defined as:

Other synonyms of beforehand include in advance.

beforehand (adjective)	ahead (adjective)
being ahead of time or need	having the leading position or higher score in a contest

beforehand (adverb)	ahead (adverb)
ahead of time; in anticipation	at or in the front
	ahead of time; in anticipation
	in a forward direction
	leading or ahead in a competition
	to a different or a more advanced time (meaning advanced either toward the present or toward the future)
	to a more advanced or advantageous position
	toward the future; forward in time