Forum OpenACS Q&A: Response to 3.2.x vs 4.x quickstart guide?

Maybe this is a good starting point. ACS Developers Guide. And the documentation for the core is not so bad!

Right now there is really no other way to figure it out, unless you want to make a big pot of coffee and browse through the SQL. Most of the new documentationn is quite good at explaining the differences from the 3.x whenver there is, and there are a lot of differences.

The data model is clear even from the docs (!) and if you play with some modules, it gets better.