As far as I know the Proud Boys haven't burned, rioted, looted and killed anyone. Nor have the taken over a section of a city claiming that it was a new nation. Then after a while that new nation had to call home for mommy to come help them because they were starving.
The Proud Boys just showed up to Antifa riots just to protect businesses and nothing more.
So they are not the same. Why Democrats think they are the same is because Antifa (they think) is on their side (they're not) and the Proud Boys are all on the right and just because of that the left says they are pure evil.
When Antifa started their "punch a Nazi" campaign a few years ago they never asked of the guy was a Nazi, a fascist, a Democrat, a anything. They just made the assumption and punched a person the knew absolutely nothing about other than he or she was white.