"In front of my car, two cats are playing."
Translation:Antaŭ mia aŭto, du katoj ludas.
There should be more questions like these, where it shows multiple ways of saying the same thing. It would help make learning alternative word orders (such as noun-adjective rather than adj-noun) much easier. We definitely don't want people from different native languages not being able to understand each other quickly in spoken conversation due to a lack of understanding of sentence structure.
Why is there a comma in Antaŭ mia aŭto, du katoj ludas but not in Antaŭ mia aŭto ludas du katoj?
I think it's only because the English translation has one. There are no strict rules about commas in Esperanto - the common usage of commas (e.g. "Mi diris, ke mi konas lin") is only a tradition that most people follow, but it's not mandatory.