n the Bohr Model, the electron is treated as a particle in fixed orbits around the nucleus. In the Quantum Mechanical Model, the electron is treated mathematically as a wave. The electron has properties of both particles and waves.
The Bohr model was a one-dimensional model that used one quantum number to describe the distribution of electrons in the atom. The only information that was important was the size of the orbit, which was described by “n” the principle quantum number.
Schrodinger's model (Quantum Mechanical Model) allowed the electron to occupy three-dimensional space. It, therefore, required three coordinates, or three quantum numbers, to describe the distribution of electrons in the atom.