Open it up and take a look at the motherboard... that should let you know if it's any different or if it's just a new case badge...
It's been a while since I've seen an A500, so I don't recall whether it said "A500", "A-500" or even "Amiga 500" on it. Do you have two side by side to verify they are different or pictures perhaps?
Regards,
Ben de Waal
AKA Yttrium Oxide
