begin vs set off

begin and set off both are verbs.

Word	Noun	Adjective	Verb	Adverb
begin	No	No	Yes	No
set off	No	No	Yes	No

As verbs, set off is a hyponym of begin; that is, set off is a word with a more specific, narrower meaning than begin:

begin (verb)	set off (verb)
take the first step or steps in carrying out an action	cause to burst with a violent release of energy
set in motion, cause to start	set in motion or cause to begin
begin to speak or say	direct attention to, as if by means of contrast
begin to speak, understand, read, and write a language	provoke or stir up
achieve or accomplish in the least degree, usually used in the negative	put in motion or move to act
begin an event that is implied and limited by the nature or inherent function of the direct object	depart for someplace
have a beginning, in a temporal, spatial, or evaluative sense	make up for
be the first item or point, constitute the beginning or start, come first in a series
have a beginning characterized in some specified way
have a beginning, of a temporal event