In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule in atomic or molecular orbitals.
Electronic configuration is the systematic arrangement of electrons in the orbitals.
The electrons were arranged (filled) into different orbitals (s, p, d & f…etc) in different energy levels (1, 2, 3, 4…etc) based on the energy. Whichever orbital posses lowest energy will be filled first.