Curious, what makes a GNR a prototype?

I see the speaker grilles are slightly different, but I don't see the translite I've seen called a prototype translite before.

not that I see any translite in the pics though :)

This auction has the translite I've seen called 'prototype' - and I like it a lot better than the 'production' one

http://cgi.ebay.com/Data-East-Guns-Roses-Pinball-G-N-R-Works-Great_W0QQitemZ280457625868QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item414c93c10c

I remember reading somewhere (not sure where) that the "proto" Gunners pin had slightly different wording on some of the inserts around the PF . Also the apron decals were slightly different (again I think it was just some wording that was different) .

In regards to that one on U.S. ebay you posted the link to ... Surely that must have been pulled by the seller or ebay . No bids at $300 U.S. ..