Mount & Blade II: Bannerlord has been in early access for a few months and TaleWorlds Entertainment has been updating it very actively. Today, they released a new round of patches. To be specific
Main difference is that the campaign is shit and adds a bunch of shite gameplay that does nothing but make the game obtuse and potentially broken. Sandbox is pretty much what the game should be. The only thing it lacks compared to campaign that could be considered good is a lack of a family member. There's a mod to give you a brother in sandbox