shortly vs before long

shortly and before long both are adverbs.

Word	Noun	Adjective	Verb	Adverb
shortly	No	No	No	Yes
before long	No	No	No	Yes

As adverbs, shortly and before long are synonyms defined as:

Other synonyms of shortly include presently, soon.

shortly (adverb)	before long (adverb)
in the near future	in the near future
for a short time
in a curt, abrupt and discourteous manner
at a short distance
in a concise manner; in a few words