Vampiric Age & Genoration

Generation Vs. Age
Generation has nothing to do with age. Generation is the measure of how many people are in-between the person and Caine. You could have been dead for 2 years or 200, but still be an 8th generation Kindred.

Age and Ranks
Fledgeling: A vampire who hasn't been a vampire for very long. Anything from a second old to a hundred, so long as the vampire in question is still considered incompetent enough in the Kindred community that his or her sire is still in total control of his or her life. Essentially, a fledgeling is any vampire who is still considered the sire's responsibility by the prince and other "legal" officials. Though most fledglings are around 0-5 years of unlife.

Neonate: A neonate is a vampire who has not been independent for very long. In America, this generally means a vampire who is somewhere between 25 and 100 years old (has spent this much time as a vampire). The vampire in question is still inexperienced and generally lives on the sufference of the rest of the local Kindred, but is considered responsible for his or her own actions, with no reprecussions or rewards for his or her behavior to his or her sire, except as regards reputation.
These Kindred are usually around the age of 6 years - 99. They have not seen their 1st century yet.

Ancillus (f. ancilla, pl. ancillae): Ancillae are vampires who have been around long enough to be viable members of the Cainite community, but who are not yet true power-players. American ancillae tend to be anywhere from  a hundred to  tw years old; in Europe, where most of the eldest vampires reside, you probably won't be considered such until 300-350 years have passed. More traditional vampires might still view most of the major Los Angeles powers (Isaac Abrahms, the "Tourette" Voerman, Gary, possibly Maximillian Strauss) as neonates, and others (Prince LaCroix, possibly Maximillian Strauss) as ancillae. In America, however, and especially on the West Coast, they are thought of as ancillae-bordering-on-elders and elders.

Elder: These are the guys in charge. In most cities you'll find an elder as Prince, and much of the Jihad seems to be run by elders. In America, 300 is a pretty secure elder; in Europe, you'll be laughed at by the other elders until you reach 400-600ish. Hardestat the Elder is an elder; Lucita and Fatima are young elders.

Methuselah: The eldest of the eldest. Methuselahs are the true masters of the jihad, with mystical powers even the elders do not understand; some have even plotted and carried out the destruction of Antediluvians from torpor (most notably, this is how Augustus Giovanni got the idea and plan). Methuselahs are unarguably a millennium or more old, and many are in a torpor similar to that of the majority of Antediluvians. Those awake, such as Mithras (childe of the Ventrue Antediluvian, and Prince of London) and Cardinal Moncada (once a member of the Manus Nigrum, and one of the Sabbat's foremost members until he was assassinated by his own childe and three Assamites, collectively four of the best assassins in the world, and all of whom nearly died in the attempt) are the most powerful vampires you may ever hope never to meet.

Antediluvians: This is the only relatively strict definition. Antediluvians are members of the third generation, either childer of Caine's childer or their diablerists. Unlike other distinctions, this ranking is not dependent on age: Augustus Giovanni was an Antediluvian as soon as he finished diablerizing Ashur, even though he was not yet a century old. Antediluvians don't have to spend millennia mastering their powers to be a force to be reckoned with (though the fact that both Ashur and Saulot managed to recover from their diablerie in a way shows that it certainly helps, especially when dealing with other Antes). Antediluvians are almost literally forces of nature with powers that seem godlike even to the most powerful of Methuselahs. For example, in game mechanics, level 10 Vicissitude (level 10 of any discipline is reserved for Antediluvians) is essentially the ability to reform one's body no matter how destroyed it may have been, even if it was tossed into the center of the sun.

The Eldest: This one isn't universally recognized, as not all vampires believe that all are descended from a single vampire. Still, canon states that a male human became a vampire without being embraced, thus beginning the lineage. He is known in modernity as Caine, and he has powers that could probably rip the very Earth apart if he truly felt like it (certainly enough to curse the Antediluvians and their entire lineages, in spite of the power and numbers they possess), but he seems to prefer being left alone to suffer his curse in peace. The Gehenna scenario essentially starts with another eternal being who has been holding a grudge for his dumping her for about six millennia, seeking him out and starting a fight.

To begin with, only Fledgling, Neonates, Ancillus ranks may be used by the PCs. As time progresses, Elders will open up and indeed, if the site grows big enough the Methuselahs and Antediluvians might even become available (future chronicles). Although active Ante's are a sign of Gehenna, the end of the world, so if or when this happens you know some bad shit's going down soon.