In English there's also a difference in comma usage with restrictive and nonrestrictive relative clauses (restrictive relative clauses, which indicate which specific entity is referred to as opposed to others, don't use commas, while nonrestrictive relative clauses, which merely add additional information, do), but I seem to remember that native German speakers will commonly write both with commas.
*The person, who was here yesterday, has come back.
Conversely, it's sometimes hard for me to remember to use that comma in German. I want to write something like *"sie sagt dass man hier kein Komma braucht".