head off vs fend off

head off and fend off both are verbs.

Word	Noun	Adjective	Verb	Adverb
head off	No	No	Yes	No
fend off	No	No	Yes	No

As verbs, head off and fend off are synonyms defined as:

head off and fend off: prevent the occurrence of; prevent from happening; to protect from or to keep away anything undesirable; to ward off

Other synonyms of head off include avert, avoid, debar, deflect, forefend, forfend, obviate, stave off, ward off.

head off (verb)	fend off (verb)
prevent the occurrence of; prevent from happening; to protect from or to keep away anything undesirable; to ward off	prevent the occurrence of; prevent from happening; to protect from or to keep away anything undesirable; to ward off