The correct answer to this open question is the following.
We do not know what the four major early civilizations that you learned about. You did not attach any reference or text.
However, trying to help you, we can comment on the following.
We are going to pick the oldest civilizations of planet earth: the Sumerians, the Harappans, Ancient Egypt, and China.
How were the civilizations similar?
These civilizations are similar in that they settled next to rivers. The Sumerians, between the Tigris and Euphrates Rivers. Ancient Egypt, next to the Nile River. The Harappans, next to the Indus Valley River. The Chinese, next to the Yellow River.
How were the civilizations different?
In that, they settled in different territories with different characteristics and developed different agriculture techniques to grow crops, and different political styles to rule their people.
Was one stronger than the other?
Probably, the Sumerians, who established powerful city-states such as Eridu, Lagash, Ur, Uruk, and Kish.