Unfortunately, some of our variation titles aren't descriptive enough on their own, but there's no Trivia to describe the variation in detail - for that, I apologize and I try to clean those up when I find them.
In this case, many of the original black box Nintendo NES titles were originally released without a Trademark on the term "Nintendo Entertainment System". Nintendo did not own it as a trademark when the system was first released. After Nintendo obtained the Trademark for the term, subsequent printings had the Trademark (™) symbol "Nintendo Entertainment System™".
If you own the System Trademark variant, it will have a ™ symbol next to the word "System" on the cartridge, as seen in this picture:
http://www.rfgeneration.c...027-S-02052-A&type=gs