There are different climates and therefore the vegetation are different depending on where the climates are. Tundra for example is prominent in the northern state of Alaska, which is marked by treeless areas and low growing flora like grasses and some flowers. Arizona where I live is both mountainous and desert, so vegetation needs to be able to store and rely on less water, so there are a lot of Cacti.
I'm sure you can find a ton of other examples.