What is the difference between the ground state and the excited state of a hydrogen atom?

(N/A) In the ground state of a hydrogen atom,the electron resides in the $1s$ orbital,which is the state of minimum energy and maximum stability.
In the excited state of a hydrogen atom,the electron occupies any orbital other than $1s$,such as $2s, 2p, 3s, 3p, \dots$ orbitals.
These excited states are unstable and the electron tends to return to the ground state by emitting energy.