Re: differences n similar btwn bohr rutherford model n quantum mechanical model

I assume you're talking about the Hydrogen atom (that's what the Bohr model refers to).

The Bohr model came first (in 1915), and was able to "explain" some features of the Hydrogen atom using the postulate that only certain orbits of the electron around the proton were "allowed". The model treats the electron as a point particle, making circular orbits around the proton, and makes a postulate that "quantizes" the radius of the electron orbit into certain specific values.

There are many features of the Hydrogen atom that cannot be explained with the Bohr model (different angular momentum states at a given energy, etc.) To get a better model, one moves to quantum mechanics (QM). In QM, the electron is not at a single location (unless you "look"!), but is best described by a probability wave that solves the Schrodinger Equation. The math gets quite complex, but you can view some of the resulting electron waves here. There are still some tiny details of the hydrogen atom which can't be explained by non-relativistic QM, but it still does an excellent job in predicting the precise allowed energy levels of the electron. (And the Dirac equation and Quantum Electrodynamics can get those last details, down to beyond the level at which they can currently be measured.)

If you want to truly "understand" quantum mechanics, you're in good company, but I'm not sure anyone really does. We know how to do the calculations, but there is still a great deal of debate concerning what the math actually means -- or what "really" is going on down there in those hydrogen atoms! As one moves to Quantum Electrodynamics, I'm afraid the physical meaning only gets more obscure.