There are some features that won't make it to Solution - but we try to keep those to a minimum. For example, most recently we couldn't bring Philips Hue support to Solution. We no longer update documentation for Solution, but we do note all of these in the release notes - so you would need to read through each of those for the "full picture".
We also made the decision a year or so ago that we would "stop supporting" Solution being used without a touchscreen (or alternatively a monitor and mouse together). Whilst most things are still accessible without using anything other than the console itself, it started becoming too complicated to design modern interfaces whilst still supporting Solution front panel hardware without a touchscreen.