Chiefly vs Briefly - What's the difference?

As adverbs the difference between chiefly and briefly

is that chiefly is (focus) especially or primarily; above all while briefly is (manner) in a brief manner, summarily.

is of, or relating to a chief.

(en adverb)

(focus) especially or primarily; above all

(focus) mainly or principally; almost entirely

(en adjective)

of, or relating to a chief

(en adverb)

(manner) In a brief manner, summarily.

He covered the subject briefly in his book.

(duration) For a brief period.

He only worked here briefly .

(speech act) To be brief, in short.

Briefly , I am not happy about what happened, but no one will be losing their job.