Honestly the purpose of them can overlap but the tools are very different in use. Vectors can come close to achieving what you want but you have to know how vectors work. ( this is a complex process if your brain does not work in that way ) Adobe is more like painting as you put down some color and go with it. You have thousands of colors to work with and creating realistic blends can be done with a fair ammount of ease. Vectors, on the other hand, tend to be selected regions for highlights, some form of gradiant to give the effect of realistic shadowing, and they normally have a limited color pallet. It really depends on the type of art you want
Game UI ( not as scalable as vector )
Splash Screens ( more complex )
Logo Design ( for more detailed ones )
So, to answer your question... either or. It just depends on the art style you like and what others feel is needed. There are plenty of indie games that use a form of vector art. Most Game UI's for tripple A companies are a mix of both so you could get a job there... but if you want to work with realistic stuff you will not use a vector system as it does not lend well to such an effect.