CORRECTION!
I've played around with SMBX, and it can't do hardly anything PB can do. PB is SUPER AMAZING. It can do incredible things, like yesterday I attempted to make custom physics, and I was able to after trying different methods, I finally reached a point where I was able to make some really cool gameplay by allowing my character to walk on walls. So, PB is the way to go. Ditch SMBX and Mario Builder today!
(I just can't help but advertise how neat PB is, I guess.)
Well, what I can understand from our conversation is that we both think very well about PB.
Maybe a difference is that you don't think that much about SMBX. Or maybe the reason why you correct me is that I didn't describe very well about where I don't like bosses very much, in SMBX or in PB.
With this video, you can see which one I was talking about and that the ways to make bosses in SMBX are actually very limited. PB actually have quite an endless possibilities to make special bosses and I even imagine what PB can do. SMBX just has a lot of developers who have tried to make the bosses look special but PB community visibly have only one member who made a very unique boss with health and behavior states etc and this is one who made Simple Quest. But PB actually is an application that can do a lot of types of special bosses without just editing the sprites.
This is just an example but PB allows us to make even big things with ease. If talking about SMBX bosses, for example, then I have seen couple things that really impressed me honestly but I wasn't able to do something like that and I am not sure if it is easier to use SMBX or a game creator application from scratch for making really good bosses.
SMBX is a very interesting tool and it has a lot of interesting games but as a developer, I exited SMBX very soon. In PB, I saw a long potential even when it wasn't released yet.