before long vs shortly

before long and shortly both are adverbs.

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

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

Other synonyms of before long include presently, soon.

before long (adverb)	shortly (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