I've always preferred hussar to cavalier...
what? ;p
I can't imagine why...
Seriously though, Hussars were not Knights (cavaliers/chevaliers).
They were light cavalry meant for skirmishing and scouting. They didn't use charging tactics, but instead used hit and run attacks. They were not trained in the lancer (though light/small spear wasn't out of the question), they were lightly armored, and they used bows from horseback.
In response to @
Corpsetaker and others, historical context does mean mechanical differences. You can't just slap a name on something then make whatever mechanics you want and consider it a done deal. Historical context and mechanics can't be divorced without the concept losing all meaning except as purely a mechanical construct...whether one cares for history or not. Even from a purely fantasy aspect, it still matters.
But since D&D is fantasy, this could be any form of mounted combat and any culture. Sticking to just European historical definitions is a silly thing in a game with elves and mages.
One culture could have mounted archer knights modelled like Hunnic and Mongolian ones.
Another could have chariot knights with a squire steering and the knight chucking spears.
Another could have discovered guns but due rarity or expense, only the mounted knights used them.
And other would have giant warbeast cavalier knights with ballistas mounted on them.
But all that matters is the mount.
Knight means a very specific cultural group of heavy cavalry.
Knight as a class name only works, even in a silly game of elves and mages, if said fantasy is Eurocentric. If not, the word loses all meaning. And, all that matters is most certainly
not the mount.
Knights are specifically European heavy cavalry, and not all heavy cavalry are
Knights.
If the goal is to model any type of mounted combatant, then the class name cannot be
Knight. Instead, the class is
Cavalry or
Mounted Warrior. Then make subclasses/archetypes for the different types:
Knight - European Heavy Cavalry, Feudal Fealty, Chivalry (not consistent across all historical periods, but consistent with romantic fantasy) - heavy chargers (lance), shield, heavy armor.
Samurai - Japanese Light Cavalry (though irregular and poorly organized as a unit), Feudal Fealty, Code of Honor; non-charging skirmishers trained in sword, melee polearms (again, non-charging), and mounted archery (daikyu/hankyu) - medium to heavy armor, no shields - Bushi-Samurai were later-period swordsmen following Bushido (though Bushido is a relatively modern term), and
not cavalry/mounted warriors
Hussar - Eastern European (Hungarian/Magyar) irregular Light Cavalry, no code (actually considered rather unscrupulous) trained in skirmishing with saber, axes, and mounted combat with small composite bows (consistent with Mongol and Turkish Light Cavalry) - light armor, no shields - occasionally spears (not lance)
Stradioti - European Light Cavalry - some charging skills (small and medium spears) but primarily skirmishers and scouts - non-archery cavalry - light to medium armor, no shields - occasionally spears (but no lance) - socially and militarily
not knights, yet medieval European mounted warriors
Cataphracts - Byzantine Heavy and Light Cavalry (died out around the 1200's) - middle-class landowners - heavy cataphracts (clibanarii) were very similar to European knights (excepting social status): heavy armor, lances, shield - light cataphracts were very similar to Persian light cavalry: light armor, non-chargers, no shields, mounted archery (unlike European knights)
Faris - Saracen Cavalry - a mix of heavy and light cavalry - trained in the charge and skirmishing, using the spear both for charging and close melee - medium to heavy armor - shields - individual training in mounted archery (trained more for individual targets rather than organized volleys) - followed a code and standard of training similar to Chivalry called
Furusiya
And there are certainly more out there...
And the first answer that springs to my mind is status, rank, leadership.
In other words, I think what we're talking about here is the elusive 5E warlord by another name.
Absolutely not.
Not all Knights were Noble.
Not all Knights were leaders. All Warlords are leaders. Not all Warlords are Warriors.
Knight most certainly does not equal Warlord.
For more, follow this conversation -
Warlording the fighter , and especially
here