If you do Not Register your Product's Name as a Trademark, aren't I Free to use that Name for My Product?
After reading laws regarding Trademarks, I can answer with certainty of.... Yes probably maybe no.
If you try to trademark something was already I use, the originator could still be permitted to use the name if they can prove they used it first and have a good lawyer and you try to prevent them from using it. So now you gotta get a lawyer to sue them.
Different markets and not direct competition, yes.
Same market but common name... Like "Milk" nobody can really Trademark Milk except maybe a cow, so yes.
Same market and a made up name that is trademarked or protected by copyright, no.
And then different markets, but you reference something else through the use of the name or image... No.
So glad I write computer code for a living, that's easier to understand then Trademark law.