write vs get hold of

write and get hold of both are verbs.

Word	Noun	Adjective	Verb	Adverb
write	No	No	Yes	No
get hold of	No	No	Yes	No

As verbs, get hold of is a hypernym of write; that is, get hold of is a word with a broader meaning than write:

Other hypernyms of write include contact, get through, reach.

write (verb)	get hold of (verb)
communicate or express by writing	affect
record data on a computer	be in or establish communication with
contact in writing	get into one's hands, take physically
produce a literary work
mark or trace words or symbols on a surface
write or name the letters that comprise the conventionally accepted form of (a word or part of a word)
write music
create code, write a computer program