Quadro cards are exactly the same as consumer cards, except the drivers for them are different. This enables certain features used in professional 3D applications. There's actually a hard mod you can do so that you can fool the drivers into thinking a GTX 680 is a Quadro K5000.
So you might ask... why is NVIDIA selling the same card for over twice the price? Here's the thing. GeForce drivers are optimized for gaming and general consumer use. Quadro drivers are optimized for CAD work. There's nothing different in the GPU level between the two applications. A GeForce isn't going to refuse CAD operations and a Quadro isn't going to refuse a draw call from a game. To them, it's all "place triangles, shade pixels". It's just that the drivers need to translate render calls from these programs appropriately.
Still, why is NVIDIA then charging over twice the price for a software change? It's the same reason why Adobe charges $500+ for its Creative Suite. These aren't meant for consumers. These are meant for professionals that make money off their products. In the end, a Quadro K5000 is going to perform slightly worse in gaming than a GTX 680 in games, but a GTX 680 is going to perform slightly worse in CAD operations.