Races may or may not have a different flavor in this world. I will include relevant PC races and some MM races.
Human - The dominant race in numbers and influence. Essentially flavorless, a blank slate for you to imprint your character on.
Half-Elf - This true breeding race is labeled Half-Elf almost as a slur. They appear mostly human with some elfin qualities that give them their name. Half-Elves are not numerous, and exist mostly in the shadows, functioning as conmen and grifters. Honorable Half-Elves exist, often rising above their brethren to work in law enforcement, or occasionally as entertainers.
Tiefling - Possessing a reputation as superb bankers and money managers, Tiefling have risen above many of the other non-human races to several positions of power. A loose network of family and professional ties have made them one of the more powerful factions in the world. While certain criminal elements do exist, a majority of Tieflings operate entirely within the law. This relatively recent surge in power has allowed them to dig into their past. Discoveries made there indicate that not only are the Tiefling not native to this world, but they are changing over time to a more 'human' appearance. Who knows what more digging will uncover...
Dwarf - Rather than attempt to integrate themselves into Human society, most Dwarves spend their entire lives in one of several Dwarven enclaves. Living on the outskirts of society, they have earned a reputation as tinkerers and occasional thieves. While it is true that a Dwarf is almost always an opportunist, propaganda and racial tensions are mostly to blame. Dwarves also have a rich cultural heritage, with songs and poems without equal in the world. Their oral history is particularly rich considering they are among the longest living races in the world.
Halfling - The most human-like of races, Halflings are also most numerous (besides Humans, of course). They thrive in urban areas where space is at a premium, and are often exploited for cheap labor. River barges and other small vessels are also filled with Halflings, generally, as their quick feet serve them well on the water. They are, as a whole, a poor and dirty race, with little cultural history of their own. Common belief is that they are descended from humans, and are slaves as their birthright.
Eladrin - The most beautiful race in the world, or so they would have everyone believe. The most visible Eladrin function as attractive escorts for politicians and businessmen. Their dirty little secret is that they are able to use their innate fey powers and their affinity for weapons to function as very effective bodyguards. Eladrin society places high value in martial prowess, and Eladrin boys and girls learn quickly or are weeded out. Children unable to participate in this training are taught in segregated schools, instructing them in Arcane and other mystical training. Like Dwarves, they keep to themselves, but they give the appearance of aloofness, rather than being cast off.
Elf - Feral cousins of Eladrin, Elves are so rarely seen that they are viewed as myth by some members of the population. Almost all Elves live in wooded areas, surviving by hunting and gathering what they need. The few elves that choose to live in society are often mistaken for Eladrin. Elves are fanatical about ancestry, and have genealogies that go back a millenia. These records end abruptly at a time the Elves are reluctant to talk about. Whether this reluctance is due to fear or lack of knowledge is unknown.
Dragonborn - Called Dragons by the populace, Dragonborn are feared for there size and ferocity. Their relative rarity is compensated for by their presence. Dragonborn dominate wherever they tread, and are seen as military commanders (under Human supervision, of course), performers, artisans, and criminals. Their numbers remain small most likely due to their wanderlust. Dragonborn are natural travelers, and rarely settle down. When an opportunity to mate presents itself, they often do, but Dragonborn have a poor reputation as caregivers, and most eggs don't hatch.