The Chivalric Orders
Paladins of Light(Paladins Paladin of Honor)- Order of the Blade (Martial build, multi-class with Fighters, and other martial classes)
- Order of the Lily (Typical build, straight paladin; 'the Face', Diplomacy Skill and Leadership Feats)
- Order of the Shield (Prestige Paladin build; fights undead and evil, uses divine spellcasting)
- White Knights, martial, 'not-worthy' of divine magic
Blood Paladins(Paladins of Freedom)- Order of the Lance (Martial build, multi-class with Fighters, and other martial classes)
- Order of the Rose (Typical build, straight paladin; 'the Face', Diplomacy Skill and Leadership Feats)
- Order of the Helm (Prestige Paladin build; fights undead and evil, uses divine spellcasting)
- Red Knights, martial, 'not-worthy' of divine magic
Black Paladins(Paladin of Tyranny)- Order of the Mace (Martial build, multi-class with Fighters, and other martial classes)
- Order of the Aurum (Typical build, straight paladin; 'the Face', Diplomacy Skill and Leadership Feats)
- Order of the Gauntlet (Prestige Paladin build; fights undead and evil, uses divine spellcasting)
- Black Knights, martial, 'not-worthy' of divine magic
Dark Paladins(Paladin of Slaughter)
Dark Knights
I know there are Prestige Classes that Wizards has made that might fit, but these are the typical paladins I divide them into.
Neither Order Paladins or Order Knights, support arcane spellcasting, and find it suspicious and abhorrent.
Paladins are worthy of wielding divine magic, and Knights are not.
The Knights outnumber the Paladins.
Paladins and Knights combine arms, with the few Paladins drawing from their own men-at-arms(Leadership), and the Knights, and the many Knights doing the same, to create sizable forces.
The Orders have different goals, with the first, the most popular and martial inclined.
The second is typical.
And the third are more elder paladins who wield divine magic.
Paladins don't have to fit in these Order, but these ones work in that fashion.
So, a paladin who claims to be of the Order of the Mace may not consider her to be a 'real' paladin, though to someone in need, it probably won't matter.
The Dark Paladins and their Dark Knights, are few in number and rise and fall, usually destroyed by outside forces, or the paladins themselves, since their existence is abhorent to all three.
In EXTREME situations, all three paladin orders will work together, without fear of losing their paladinship for associating with one another.
An extreme situation would include destroying Dark Knights.