look back vs look backward

look back and look backward both are verbs.

Word	Noun	Adjective	Verb	Adverb
look back	No	No	Yes	No
look backward	No	No	Yes	No

As verbs, look back and look backward are synonyms defined as:

look back (verb)	look backward (verb)
look back upon (a period of time, sequence of events); remember	look towards one's back
look towards one's back