I think Lionel's Engineering team is trying to make their newer LEGACY electronics DCC compliant. MTH's DCS is considered dead right now with MTH going out of business. DCS is a clunky proprietary DCC system anyways. If I was you stick with DCC and the newer Lionel Legacy items. Convert older items to DCC and such.
Conventional items are non command control items, they run off track power voltage with a transformer.
This is my opinion. I'm slowly converting my older items to DCC. My future layout will be set up to run in DCC and standard O gauge AC command environment.