what's the difference between the aufbau principle and hund's rule?

When we fill electrons in shells, subshells and orbitals we use three important principles or rules.
First is Aufbau principle according to this rule or principle -Eectrons are filled in increasing order of energy means you are going to fill electrons in the lowest energy shell or subshell first and then to next higher and next higher. As we know principal quantum number and angular quantum number controls the energy by formula (n+l) so electron should go in all elements first one s and after that in 2s then in 2p and so on .
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Pauli  exclusion principle-
An orbital cannot accommodate more than two electrons in it.
We know that electron can spin only in two directions- clockwise -anticlockwise so when we fill electrons inside an orbital they have same  charges so they tend to repel each other. This repulsion can be minimized only when they are spinning in different directions so that is the reason you cannot have more than two electrons inside an orbital because there are only two spinning directions. You try to put  3rd electron inside it then the third electron will have a spin similar  to any one of them which are placed earlier. This can cause too much repulsions inside the orbital and will make it unstable.
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Another rule is Hund's rule
When we have orbitals of same energy level in a subshells  like p subshell has three orbitals in which are  exactly same in energies, d -subshell has five orbitals, and  f has 7, then electrons must be filled first with parallel spin (unpaired) in all of them and then pairing starts.
Once all of orbitals of a subshell have one electron each then pairing starts means t when you are going to fill three electrons in a p orbital then they will go 1  in each p orbital with parallel spins ,if you are going to fill 5 electrons in the d-orbitals then you are going to fill them singly in-5 parallel spins electrons in 5 different d orbitals
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