Homonyms can be further broken down into homophones; words that are pronounced identically though spelled differently, and homographs; words that are pronounced and spelled identically. In both instances of homonymy the requirement is for the common words to have unrelated meanings.
bare - to uncover
bear - the mammal
bank - the financial institute
bank - the side of a river
In the case of polysemy, the reference is to a single word with different senses of the same basic meaning. Polysemes are also distinguished from homonyms because they are etymologically related.
Polysemes:crawl - to move slowly on hands and knees
crawl - to move slowly in traffic
crawl - to be covered with moving things
crawl - to swim the crawl