D&D 5E XGTE has the Samurai Subclass

[Wrathamon]

Knights rarely if ever used bows in battle. Samurai often did.

This is a moot point however since there is little about the Samurai class that well represents historical Samurai. Which Mearls was very up front about in the video.

for me that is weapon choice ... proficiencies that the fighter already has ... choose Archer fighting style for your "Samurai" and take the archer feats. everything else to me can be mechanically the same its the theming. If you want your Samurai to be mechanically different than a Knight ... it seems like they are both filling the same "space" But, it's my opinion so I know it's not the same for others. Samurai for some reason fall into the category of Ranger ... everyone has a different idea of what it should be.

 

[BookBarbarian]

for me that is weapon choice

Right. Different weapon choices are a difference. Or were you only asking what mechanically would be the difference between an Historical Knight and an Historical Samurai being represented in 5e?

I took the question to be a general difference between Knights and Samurai.