Hi Marika, I am an italian girl. I study languages at university and I m conducting a work on the Homonimy.
For this reason I have studied very accurately the difference between homonimy and polysemy so I can help you.
Homonyms are those words without any semantic connection while polysemy is based on a metaphorical extension. This means that two words can have two different meanings but linked between them
For example "newspaper is a polisemantic word
It means not only the object you read but also the place were people work
While try to check on a dictionary the word " beetle", you will find 5 different meanings that don't concern each other: they are homonyms
Is it clear?
Hope helping you
bye