Here’s what it really comes down to for me:
Peleton is spin classes. Zwift is group rides and races.
Peleton is for people who want to exercise/get fit. Zwift is for cyclists.
I realized the big difference while watching a TV show that had a character in a spin class.
Peleton is, “Come on, you can do it! Feel that burn and know you are improving your life!”
Zwift is, “Hey…looks like you can work with me to catch that group ahead. Oh…you’re cooked? Peace out…I’m gonna drop you and find someone else who can take me further up the road.”