London penetration depth in superconductors and skin depth in conductors share similar mathematical formulations derived from Maxwell's equations, but they are not equivalent. The skin depth arises from dissipation effects due to finite electrical conductivity, while the London penetration depth is linked to the effective photon mass in superconductors through the Anderson-Higgs mechanism. Practically, they exhibit some similarities, yet one cannot substitute penetration depth for skin depth in electromagnetic property calculations. Superconductors at low frequencies behave like perfect conductors, with the key distinction being the presence of significant kinetic inductance in type II superconductors. Understanding these differences is crucial for accurate electromagnetic analysis in superconducting materials.