in short vs shortly

in short and shortly both are adverbs.

Word	Noun	Adjective	Verb	Adverb
in short	No	No	No	Yes
shortly	No	No	No	Yes

As adverbs, in short and shortly are synonyms defined as:

Other synonyms of in short include briefly, concisely, in brief.

in short (adverb)	shortly (adverb)
in a concise manner; in a few words	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