Complex sentence: The brothers had a large following, and some fans compare them to the Marx Brothers, but the Ritzes didn't play contrasting characters like the Marxes did; the boisterous Ritzes all behaved identically, making it harder for audiences to tell them apart.
Split into simpler sentences: The brothers had a large following, and some fans compare them to the Marx Brothers. But the Ritzes didn't play contrasting characters like the Marxes did; the boisterous Ritzes all behaved identically, and sometimes it was hard for audiences to tell them apart.