Also a B3 fan but it’s really personal preference. It’s been a long time since I did PureBarre so maybe it’s a little different now but from what I remember it was all small movements and a whole lot of techno beats lol.
B3 incorporates more cardio as PP mentioned and generally has bigger range movements. They also now have strength classes which I love- has really encouraged me to start using heavier weights which I was previously intimidated by. Instructors are great and offer a ton of modifications and extra pushes so you can feel successful no matter where you’re at. It’s true some of the instructors can be “inspirational” but it varies and I do a lot of yoga too so it doesn’t bother me