Is this a run on?
One group looks like a bear another is like a lion.
I am confused.
Yes. That's a run on sentence. Each of these should be a separate sentence:
One group looks like a bear.
Another is like a lion.
You could also join these two sentences with AND.
One group looks like a bear, and another is like a lion.
one group is a horse.
the next group is a dog.
join the sentenses and you get:
one group looks like a horse and the other looks like a dog.