The correct answer to this open question is the following.
The two similarities and differences between an ancient Roman circus and the ones that we see today are the following.
Similarities.
1.- Both were made for entertainment purposes, although entertainment in ancient Rome times meant something very different and cruel.
2.- It included people, acts, and animals, although as I said above, the shows were cruel, aggressive, bloody, and deadly.
Differences.
1.- The circus seated thousands of people. The circus buildings like the one in Rome were huge. According to historians and archeologists, these circuses seated 15,000 people (The small ones) to 80,000 to 100,000 people as was the case of the Roman Circus.
2.- Roma circus were open venues, did not have a tent, like a modern circus.
The Roman circus presented gladiator fights like the ones we see in the movies. But they indeed were mortal. People were killed in the fights, They also released big cats such as lions and leopards that had to be hunted by fierce warriors or the animal killed people. Something very bloody.
