Question

Are the general relativity and quantum physics different and if so then how

Answer 1

General relativity and quantum physics are different
Historically, the problem was a technical one. After theorists found methods for applying quantum theory to particles (the Schrödinger equation and the Dirac equation) they sought a method for applying quantum ideas to fields (such as the electric field, the weak field, and gravity). They came up with a general way to do that; technically it was called "second quantization." You can read about it in any graduate level textbook on quantum field theory.

But this approach had a serious problem.  Many of the calculations gave infinite answers. Schwinger and Feynman and others came up with a way to solve that problem, called "renormalization." In its most simple version, it consisted of separating out the infinite terms, arguing that those are terms that exist even in the absence of the phenomenon that you are interested in, and then throwing them away.  It's reminiscent of Dirac saying that the vacuum is full of an infinite sea of negative energy electrons which we never notice; just ignore it and you're OK.

But renormalization failed for gravity.  It was related to the fact that to be compatible in the non-quantum limit with general relativity, the exchanged particle in gravity would have to be a spin-two particle, one that we call a graviton. But the renormalization method didn't work.

Nobody ever liked renormalization, but it was very successful. Ignore the infinite part, and you get the right answer!  Everyone hoped that eventually we'd look deeper and in the final theory, we would be able to get finite answers without using this cheat.

That is part of the reason for the original excitement over string theory. It gave the same answers as quantum field theory, but without the need for renormalization.  Wow!  But was it the right theory?  It had lots of other problems.  But gravity did not seem to be one of them; it appeared to be a natural part of the theory.

Answer 2

it's the physics that explains how everything works: the best description we have of the nature of the particles that make up matter and the forces with which they interact. Quantum physics underlies how atoms work, and so why chemistry and biology work as they do.