Rolex 24 at Daytona features 4 classes of cars. What does each mean?

Can't tell the two prototype classes apart at Daytona's Rolex 24? Or the two GTD classes? If all else fails, find the color ...

24 Hours of Daytona features 4 classes of cars; let's meet them | GTP, LMP2, GTD Pro, GTD

Can you tell the differences between the two prototypes in the Rolex 24? How about GTD and GTD Pro? This might help. Or might not.