As adjectives the difference between thiefly and chiefly
is that thiefly is (obsolete) like a thief; thievish while chiefly is of, or relating to a chief.
As adverbs the difference between thiefly and chiefly
is that thiefly is (obsolete) like a thief; thievishly while chiefly is (focus) especially or primarily; above all.
chiefly
English
Adverb
(
en adverb)
(focus) especially or primarily; above all
(focus) mainly or principally; almost entirely