I have used both Pbpro and Proton, now I only use Pbro for old project support and all new work is in Proton. This opinion on the differences is my own thoughts, I do not want to get into a flame war over it!!

IDE
The IDE looks the same as in both compilers but Proton has plug-ins. This enables people to write add-ons like PDF management systems, wizards etc.

But an IDE is just an IDE and note pad will do if you have to.

The compilers both do not support reusable variables, however this has never been a problem for me as I can keep in my mind what is used were and have never run out of variables.

The both do not support functions etc. But my coding style is such that I never need them a gosub is all that is needed. Functions have over heads and they can really take a toll on code space so even if they had them I would not use them.


Code usage/ Speed etc
Proton code is smaller and this can make a big difference with large apps.
Proton is faster due to the above but no one would notice. Your coding style would make a much bigger influence on both code space and speed.

Variable types etc
Proton supports all Pbro does and adds Floats. Pbpro support for Dwords or longs is a waste of resources. As soon as you use Longs code usage goes through the roof as all sums etc are done as a long. Proton is a much better compiler when using larger variable sizes

Commands
All the usual stuff are there in both. Proton adds GLCD support so if you want to start a project using a GLCD your better off in Proton. I find Protons support for USB easier than Pbpro but thats just me I'm sure others will disagree. Proton now adds a Pre-processor in the next release to add to macros.

Forum support
I see that Pbro has more basic coding questions, Proton you get a lot of discussions on non coding related stuff. It might just be me but they seem to be more willing to pass code around. Pbro has more users so they should be more help on hand. I have never ask so cannot comment on that to much.

Price
Well Proton is better value but you have to look at the whole package, what else do get in the way of support. I cannot comment on that as I do not have the need for that much.

I use Proton a lot with other packages like ISIS for its VSM which make the whole project experience a lot easier.

Ultimately both are long established products with a good history.