Orbitals are regions of space around an atomic nucleus where there is a high probability of finding an electron. They are represented by mathematical equations and can hold up to two electrons with opposite spins.
Shells are energy levels within an atom where electrons can exist. They are labeled with the letters K, L, M, etc. and correspond to the number of the energy level (e.g. K-shell is the first energy level).
Subshells are subdivisions of shells, designated by letters such as s, p, d, and f. These letters correspond to the shapes of the orbitals within the subshell.
Orbitals refer to the specific regions of space where electrons are most likely to be found, while shells refer to the overall energy levels within an atom where electrons can exist.
The shapes of orbitals are determined by the mathematical equations that describe them. These equations take into account the forces acting on the electrons, such as the attractive force of the nucleus and the repulsive force of other electrons.