How are prairies & meadows alike and different?
Well, the plant communities are often different to start with. Perhaps one of the most important reason for this is that prairies are dependent upon fire to to keep their particular plants thriving. Most prairie plants (like the grasses) have very deep root systems that survive fires. The burned plant material is converted to nutrients that go back into the soil. Meadows are more reliant - and resistant to flooding. Their plants are adapted to a different set of environmental circumstances.
Here is an excellent publication that explains in greater detail the differences between these two ecosystems: