Dinis makes a good point about the confusion that one can encounter when moving from earlier versions (pre-8.5) of AppScan Source and AppScan Enterprise to 8.6.x and does a pretty solid job of explaining the line in a bit more detail.
To help out with his one point of confusion, regarding the Dynamic Analysis module, I gave him a bit of an insider explanation, which may be useful to others:
"I agree this is a little difficult to understand at first, but
you basically had it about right on your blog when you venture 'I would say that it is the AppScan Standard engine running as a web app'
Basically, when we 'combined' the Source and Enterprise servers, we added each scanning
capability as a separate item that you installed on the Enterprise Sever. So
now you can have just Source running on it, but if you want the previously
included web based dynamic scanning (which was the main function of Enterprise),
then you need to also install this dynamic analysis scanning module as
Hope this helps a bit. "