List three things that make the states different from one another:

Laws, Geography, government

Explanation:

What's your home country? Many countries have provinces within them with each province having its own local government and regional culture. Ireland has counties - each one different from the next. Ireland's counties are not nations - the U.S.'s states are not nations.

Though there are nations in the world much smaller than the state of Texas. But yes - the 50 states are not all that united. They live under a common government national government but the character and culture of each of the 50 states is distinct from the rest and some states representing extremes - comparing Texas to Massachusetts would be an extreme comparison. Comparing Oregon to Florida would show you two states very different from each other.

The geography of the U.S. alone would show you the first reason why the 50 states are different from each other. Nevada is a desert and Virginia is not. Colorado is very mountainous and Kansas is very flat. Florida is very hot in summer and warm in winter and Maine is warm for about two months in summer.

I'm not sure where you've gotten the idea that the 50 states are so -united - politically they are also represent extremes though they coexist under a common federal government.