Junk is an algorithm and learned information that does not, never has, and never will use the from email address as a basis for it's decision making. Spam is sent from random addresses, including those of hacked friends. unwanted mail often comes for the same address, but this is the sort of mail that you can unsubscribe from.

Thanks for this definition of "Junk". I investigated "creating filters" and was able to create a filter that moved unwanted mail to "Junk" under "Local Folders", and this is working. I will probably be using this more from now on!