Just to be 100% sure. Can I put L480 motherboard into L580 no problem?
According to parts lists, yes.
Great, i was confused cus l480 Mobo is half the price of the same spec described as l580 mobo
Yeah they seem to be identical. The model number and serial will match that of an L480, so you should most likely install L480 drivers and L480 bios updates, not those for L580 afterwards