Well, how mobile games and PC/Console games are developed, the entire process is very different. So the companies who make mobile games employ totally different kind of employees and have a different infrastructure when compared to the other ones.
But here’s a thing…
These days almost every big game developer is offering their products for all devices, from large screen to hand-held devices. On the other hand, at large, you will find many independent mobile game developers are usually small in size and try to make money out of banner advertisements. Their expense is much less, plus they combatively struggle with graphics.
In short, to answer your questions, these two types of companies use different development techniques, employ different types of experts, have two distinct consumer base, and most importantly, they have different revenue model.