Although I've only used the one from the OW Travel Planner link for a few minutes, it does have a more modern UI; it offers a schedules and Itineraries facility with the latter perhaps more friendly than before; it's version is 3.0.0.4 with data version 1.0 and is written by Innovata.

I'd say that it basically looks to be just an improved version...so I suspect OW have switched the contract for providing this to Innovata.

Both are missing what would be a most useful feature for xONEx planning - indication of cabin classes available.