Final answer:
The principal characteristic that differentiates temperate and tropical rainforests is latitude.
Step-by-step explanation:
The principal characteristic that differentiates temperate and tropical rainforests is latitude. Latitude determines the position of these biomes on the Earth's surface, and it affects the amount of sunlight, temperature, and precipitation they receive. Tropical rainforests are found near the equator, between the Tropic of Cancer and the Tropic of Capricorn, while temperate rainforests are located in temperate regions, typically between 30 and 50 degrees latitude.