You're correct - at the moment we only produce one set of reference documents. The means that you don't have to worry about switching between docs to compare features. We're currently reviewing our whole docs offering - including adding which API elements are available in the difrerent versions to avoid any confusion.
At the moment, we have a matrix on our pricing page that to check which features are included and we're looking at other options.
Sorry for any confusion - if you do have any questions please do ask.