realize vs understand

realize and understand both are verbs.

Word	Noun	Adjective	Verb	Adverb
realize	No	No	Yes	No
understand	No	No	Yes	No

As verbs, realize and understand are synonyms defined as:

Other synonyms of realize include realise, see.

realize (verb)	understand (verb)
perceive (an idea or situation) mentally	know and comprehend the nature or meaning of
be fully aware or cognizant of	perceive (an idea or situation) mentally
make real or concrete; give reality or substance to	believe to be the case
expand or complete (a part in a piece of baroque music) by supplying the harmonies indicated in the figured bass	make sense of a language
convert into cash; of goods and property	be understanding of
earn on some commercial or business transaction; earn as salary or wages