DNF 2.0 has been in development for a while and one of the early on changes was making use of libdnf rather than Hawkey/libhif but this new version does bring some incompatibilities with DNF-1. DNF 2.0 also delivers on user-experience improvements around better reporting messages of dependency problems, weak dependencies and more intuitive help usage. DNF 2.0 also removes some earlier Yum incompatibilities but at the same time does bring some breakage compared to DNF 1.0.
The Repoquery plugin has been moved into DNF itself and there are also more than sixty fixes to the DNF stack. More details on DNF 2.0 and DNF-PLUGINS-CORE 1.0 can be found via this release announcement.