The light raiding dreadnoughts (Fed DNL, Klingon C-5, Romulan Shrike, etc.) were the largest of the pre-General War flirtation with "fast raiders". They use normal dreadnought engines on hulls that have been modified to streamline their warp bubble and had mass removed (and sacrifice some heavy weapons, typically).
The heavy dreadnoughts were a late-General War type. They add additional power systems and weapons to the existing dreadnought hulls. Some had external changes (the rear hull on the Fed DNH was "stretched"), some did not (the Klingon C-10 is pretty much externally identical to the C-8/9), some just have token added sponsons, etc.
As-noted, these ships are indeed in Federation Commander, but the cards are not necessarily online in Commander's Circle for free.
The DNLs seem to be a definite for ACTASF, since the Fed DNL is already shipping and the Klingon C-5 renders are up for review.
The DNHs are an unknown. Many of them just don't look any different than the stock DNs they were refitted from, so (given that Mongoose has a stated desire to do unique miniatures) they may not end up in ACTASF. Or, they may. Only Mongoose and ADB can really decide that.
