What I think will be good about a WoD game is that unlike a lot of the traditional RPG games it's not focussed on gaining skill points and levelling up, it's more about roleplaying, climbing the ladder of vampire politics interactng with the other characters. It's not the sort of game where you acquire all these mega magic item max out all your levels and go around PKing everyone in site.
Wrt to the differences between Masquerade and Requiem: the way clans work is a bit different now, Basically it's split up in two:
Firstly you have the clan, which represents who sired you, what your lineage is etc. There are 5 clans (ranging from Nosferatu, which are the disfigured monsterous type vampires, through to Ventrue, who are sort of the elite aristocratic type group), the choice of clan affects your appearance, the disciplines you have access too and how the outside world percieves you. Within the structure of the clans there's also the idea of a 'Bloodline', which are kind of off shoots of one of the clans (Morbus are a good example, they are a bloodline of the Mekhet clan, that has 'mutated' over the centuries, they are only able to sustain themself by feeding on the blood of the dieing or disseased).
The second part is the idea of a covenant, the covenant is basically a political organisation, which represents your characters beliefs and idea's. There are 5 covenants + an extra 'unaligned' grouping. Each of the covenants have a different goal ('The Carthian Movement', is kind of like ultra liberal democratic sort of vampire society, its members believe vampire society needs to adopt ideas from Mortals, they are kind of like the reformists of vampire society. The 'Ordo Dracul' are a kind an estoic order formed by Dracula, who believe it's possible to transcend the curse of vampirism and become mortal again, so most of there actions revolve around finding a cure for vampirism. Then there's the 'Lancea Sanctum' who were formed by Longinus, they are kind of like a maleformed christian sect who believe vampires have been choosen by god to enforce he's will, they believe that their purpose is too demostrate what happens when people stray from god's will and consider it heretical to suppress the vampiric urges).
Your clan kind of affects what role you have within the covenant, so Nosferatu and usually spies, Mehket are information/intelligence, Gangrel are the enforcers\muscle etc.
The vampire powers you get (called disciplines) are affected by both your clan and your covenant.
Ther are two common types of disciplines, physical and psychic (stuff like Resilance, vigor, Obfuscate) and then there are the unique discplines that the clans have access to eg (Mehket get Auspex discipline, related to their enhanced insight. Nosferatu, get Nightmare discipline and are able to manipulate the fears in others). Some of the covenants grant you powers if you advance far enough along them, eg. If you advance far enough through The Ordo Dracul you can eventually overcome some of the vampiric weaknesses, like being able to stand in sunlight for a limited amount of time and things like that. The rarest disciplines are specific to a particular bloodline and can take years to emerge, to use the morbus as an example, eventually they can gather the power to spread dissease.
All the covenants mingle together within the city (called a domain) and try to influence the decision of the prince (ruler of the domain) in various ways.
I guess people reading this are going "so how is it any different to generic rpg X with races and classes" the major thing that makes V:TR stand apart is the idea of a blood potency, the more blood you consume the more powerful the blood you need to consume to survive. So a newbie vampire can gain sustance by feeding off animals and things but eventually they need to move onto humans to survive, as you increase in power (eg skills) the blood potency goes up until eventually you have to start feeding off other vampires to gain sustance (which is forbidden and punishable by death in vampire society). This has a sliding scale as well until eventually you'll only be able to survive by feeding off master vampires. To counter act this a vampire can voluntarily (or is sometimes forced) to enter a kind of hibernation (called torpor). While in Torpor you start loosing power (stats decrease) and your blood potency is lowered until you can sustain yourself on regular humans again.
This will make the stats/levelling side of the game really interesting, eventualy a charcter will reach a certain point where you will have to make the choice betwen going into hibernation and loosing some of your abilities or attmepting to feed off another vampire in secret in order to level up further. So once a character starts getting uber powerful he won't be able to remain that way for very long.
Feeding off a vampire also grants you extra powers, eg if a newbie vampire fed off an older vampire they would gain skills a lot quicker then they otherwise would because their blood potency would be so high, if caught though it would have pretty servere consequences. This would make the PVP aspect of the game really interesting. At least for vampire vs vampire combat.
The RPG also has the idea of morality (humanity for vampires) and derrangements. The higher your humanity the easier it is for you to get by in the mortal world and pass for human. The derrangment side of things is pretty interesting as well, say your character gets trapped in a burning building and comes near to death, there is a chance you'll develope an derrangement like an unnatural fear of fire (eg if you see a fire, someone lights a match near you, you smell smoke etc, theres a chance you'll either freeze up and be unable to act or go into an uncontrollable frenzied rage). In the game I gm'd one of the characters was captured and tortured, as a result he developed an intense fear of knives, if someone pulled a knife or a sword on the character he usually reacted very badly, often going into a frenzy.
If they can incorporate things like this into an online RPG it will certain be unique from most other games out there and thats just the vampire side of it. The other supernatural beings (Mages, Werewolves etc) have their own societies rules etc. Eg. Mages are forbidden from using 'vulgar' magic in front of other non mages etc.