Penetration power is the ability of an electron to get close to a nucleus.
Electrons in different orbitals will have different penetration power because it is dependent on the shell and subshell.
Within the same shell, the penetrating power of orbitals follows this trend:
s >p >d >f
And for different shell and subshell, penetrating power of the orbitals follow this trend:
1s >2s >2p >3s >3p >4s >3d >4p