The comparison essay is what compares like things.
I will use a couple of examples below to give you an example.
1) Grizzly Bears vs. Black Bears
- They are both bears
-They both eat berries and hunt for fish
- They both raise young in the den and then teach them how to survive on their own.
-They both will protect their young
2) Snow and Rain
- They both are types of precipitation
- They both occur with clouds
-They both can be cold
-They both can happen anywhere in the Northern Hemisphere
The contrast essay provides the differences of two things
1) Grizzly Bears vs. Black Bears
Grizzly Bears are more scared of humans and will shy away from communities with people in them, as black bears will go more towards communities
Grizzly bears are poor climbers, whereas black bears are more versatile with climbing trees
Grizzly bears dig for clams where as black bears hunt more for fish and berries.
This just gives you some hints about comparison and contrast.
You could also ask your instructor if you can do both.