When it has lycra it is great for knit tops, dancewear, costumes, dresses and more.
Velveteen is a woven velvet fabric with a short, dense pile and is usually made from cotton. It has more body, making it best for jackets, blazers, dresses, skirts and pants.
Velour is another form of a velvet knit. It usually stretches, but does not have lycra to make it stretch back to it's original form. It has a soft cotton-like hand versus the more synthetic and slick feel of stretch velvet knit. It's best for loungewear, tops and robes.
Velvet also comes in other contents such as rayon. silk, polyester and acetate. They are normally woven and have a very luxurious look to them. They can have embossing on the surface and can have a burnout look. The burnout velvets usually blend of silk and rayon. These kind of velvets have more drape than velveteen making them suitable for blouses, dresses, kimonos, wraps and skirts.
All velvet has a nap, which is very important to know when you're cutting out a garment. You want to make sure all your pattern pieces are going in the same direction.