but right off the bat I think they're different because Greco's are Nickel and Orville's are chrome.
Correct. The Orville pups are alledgedly of US origin ("Orville by Gibson") and they sound great, but as others have pointed out, the Greco pups are hotter and have wonderful growl. The Orvilles have the same neck profile and pickup placement as Gibsons, whereas the Greco birds have a more P-bass like neck, and the pups on the two pickup models are spaced differently to Gibbys.