All gases have different densities, but under constant conditions (T, P, n) all gases will occupy the same volume.
molar volume = molar mass / density
molar volume of He = (4.00 g/mol) / (0.162 g/L @ SATP)
= 24.8 L /mol
molar volume of Ne = (20.2 g/mol) / (0.815 g/L @ SATP)
= 24.8 L/mol
Do that for any gas and the molar volume will be quite close to 24.8 L/mol @ SATP.
I don't have the densities @ STP on me, but when you do the same calculations with those the molar volume will be 22.4 L/mol.