On the Adobe website it says that people using the new Indesign CC software can publish to the new 'Digital Publishing Solution", not to be confused with the old "Digital Publishing Suite"...
but it seems the new DPS is a paid/subscription only service and regular users are not able to use the new 'Solution' portal. They can however use the old 'Suite' portal to test documents and publish to iPad etc.
DPS Classic publishes folios (ie: an 'issue') into a classic app. This app is fixed layout - ie: has a generic look like all other Adobe DPS Classic apps. You can also add an html kiosk storefront to the binary app, to enhance the main home screen, however this can be time-consuming and costly. You can use Indesign CC to create your layouts, or HTML, or PDF. And you still have to use the Folio Builder to create your issues. And then publish via the Folio Producer. A good example is the current UK Wired magazine, or GQ UK, and BBC Top Gear. Once you submit your app to Apple or Google etc, that's the app locked down until you next submit. Adobe will continue to support this system for the time being as far as I understand it - but I would advise moving up to the new 'Solution', as its totally brilliant, and that's where their focus will be from now on, I am sure.
DPS 2015 (Adobe's new Digital Publishing Solution) is a new way to publish digital content - you can publish single articles, collections (groups of articles). You can also feature banners, and the app main browse paage can be changed as many times as you like. For example one can update on an minute-by-minute basis - ie: create a news feed, and also change your browsing pages as you see fit. Its highly flexible and offers much more compared to Classic. You can use HTML via a variety of solutions via the DPS Content API - Wordpress, Woodwing Inception, Drupal, and loads more CMS solutions, giving you more flexibility in the tool that you use in your organisation. You can still use Indesign CC of course, and also import in PDFs. Great examples of the new DPS 2015: Qantas, Swiss Air, The Times Weekly (USA), Shell. The browse pages are designed using the innovative Layouts and Cards feature - and its all 'live' - meaning the customer sees a more enhanced, freshly updated experience. You can also choose to publish to phone, tablet or both. Its flexible dependant on your needs...
I'd advise have a trial on the system - it takes a while to pick up - but once you do there is NO going back, because it rocks.
On the enterprise vs single account - this is no longer relevant - speak to your local Adobe partner or Adobe contact and ask about a new DPS license for your needs.
Suite used the paradigm of periodical publishing. You built "folios" which contain "articles" and sell/give access on a folio basis. This was great for the periodical (magazine) model -- but it delivered the content as monolithic downloads. Depending on the period of your production, your readers downloaded one big thing with all the articles for that release. They read it, but rarely returned to the content between publishing cycles.
Solution allows publishing individual articles at anytime, and an article might be in more that one place (collection) within an app. Atomistic publishing rather than monolithic publishing. Frequent publishing helps bring readers back into your app more frequently.
That's the big difference, perhaps philosophically.
If you're using InDesign to build "pixel-perfect" articles, you can use many recent versions of InDesign to export article files. But if you have a DPS 2014 app (it uses the Suite system,) the latest version of InDesign cannot be used because the Folio Builder panel doesn't exist for InDesign CC 2015.
You're right that DPS 2015 is a paid/subscription service. And while the older workflow is more open at the learning level, you'd also need to pay/subscribe to DPS 2014 if you want to build and distribute an app.