What are light tarot cards and dark tarot cards?

That depends on where you heard about it. If movies and games and friends around you tell you, you don't need to believe it. After playing tarot cards for so many years, I have even seen more than N brands of tarot cards, but I have never heard of any bright and dark tarot cards. To be exact, there is no such thing in the world of tarot cards. The only possibility is that bright represents good cards and dark represents bad cards (well, this is just my guess), but you don't have to pay too much attention.

I hope I can help you ~