A gladiator background maybe gives you proficiency with an exotic weapon. Anyone could have been a gladiator -- your elf wizard, for one. A gladiator specialty might focus on flashy combat moves, toughness, and melee tricks. Your elf wizard can still do this, though maybe it's a better choice for, say, your halfling rogue. A gladiator subclass is for those who want to define their character mostly as a gladiator. Maybe a better fit for your half-orc.
See, I find this quite inelegant (just like I do the Tri-Vampire), because I personally believe the fluff should mean something. Something specific. If you can be a "Gladiator" just by taking a feat that has you wielding a trident and net, even though you're actually an elf wizard... then no, I think then having another Gladiator being a specific type of Fighter is inelegant. Pick one or the other. But don't have both. It's my exact complaint with regards to the Fighting Styles / Specialties issues I've talked about in other threads... where you could be a Marksman *and* a Sharpshooter. Or a Reaper *and* a Slayer. Both of them fluff out the exact same way, even though they theoretically should be two different things (since one is a specific fighting style that only a trained Fighter can use... and the other is some random collection of moves that anyone with a weapon in their hand can use.)
Having fluff connecting to your character should mean something. And I don't think that occurs when one character can be a Marksman Slayer and the other is a Reaper Sharpshooter. If you look at them within the game world... there's no appreciable difference. Which I just think is rather ugly design. And the same holds true for the Three Faces Of Vampire. If you have a feat that makes you a Vampire... then are you
less of a Vampire than someone who has the class of Vampire? Since you have less Vampire abilities, shouldn't you be a Lesser Vampire? And if Vampire can also be a race... then how come we no longer have the Dwarf or Elf class anymore? Shouldn't that be the case, if you can have a race and a class be the exact same thing? If we have a Vampire that can be a race or a class... then we should have the Human as a race
and a class too, right? I don't see any real difference there.
I can understand why it doesn't matter to some people, like yourself. That kind of... disconnect... probably only affects certain types of people (like myself). But I can't help it. When I see the word 'Wizard' in the game... I like that it means only one thing. When I see the word 'Stealth' in the game... I like that it means only one thing. When I see the word 'Dimension Door' in the game... I like that it means only one thing. It's clear. It's understandable. It gives me a direct visualization into what we're all talking about.
But that doesn't happen when you say the word 'Gladiator' in the game... and we have no idea if you mean a class or a background or a specialty or just a random term we throw out onto an NPC because in the story he's a slave who fights in an arena. It's a Fluff term used to describe something that doesn't necessarily ADD to the fluff of who your character is. Not when there are another four to six OTHER fluff terms already layered upon your character based upon race, sub-race, class, sub-class, background, and/or specialty.