photomicrograph vs photo

photomicrograph and photo both are nouns.

Word	Noun	Adjective	Verb	Adverb
photomicrograph	Yes	No	No	No
photo	Yes	No	No	No

As nouns, photo is a hypernym of photomicrograph; that is, photo is a word with a broader meaning than photomicrograph:

photomicrograph: a photograph taken with the help of a microscope
photo: a representation of a person or scene in the form of a print or transparent slide or in digital format

Other hypernyms of photomicrograph include exposure, photograph, pic, picture.

photomicrograph (noun)	photo (noun)
a photograph taken with the help of a microscope	a representation of a person or scene in the form of a print or transparent slide or in digital format