Well, there are a lot of ways to distinguish between these two animals, most of which are pretty obvious and visible, especially if you take the time to Google some images. However, I'm going to give you the benefit of the doubt and list some of the most noticeable differences.
Bats are mammals, whereas penguins are birds. Bats are warn-blooded creatures with fur and hair. They are also capable of becoming pregnant and giving birth to live young. Most notably, they nurse their young and produce milk. Penguins ,on the other hand, can't get pregnant and lay eggs. They are also warm-blooded, but have feathers instead of fur and are not capable of producing milk for their young. Furthermore, penguins thrive in cold climates, but bats do not. Finally, bats have wings and are capable of flight, whereas penguins can't fly. Their wings aren't used for take-off - instead, they're used to steer them when they're belly sliding, or used to swim in water.