They do not use the same electronics. It's just the same pickups. Pots, switches, and even the pre-amp, are cheaper.
They do not use the same hardware throughout. They use the same imported bridge plates; that's it. All the other hardware is different (bridge saddles, tuners, knobs, strap buttons, string retainer, neck mounting ferrules, screws).
They are not "a lot less." With used Tributes going for $500 to $700 these days, and used U.S.A. models from G&L's good years going for $1,000 or less, you're talking about waiting just a little bit longer to save up and buy a U.S.A. model for $300–$500 more. As such, Tributes are not even worth it unless you can get them for $300–$400 including tax and shipping, IMO.
Tributes are perfectly OK in their own right, but if you really know the market for used U.S. G&Ls, then you know that the Tributes are a false economy, in comparison. Why on Earth would I even think about spending $500–$600 on a Tribute L-2K, when I was easily able to buy a beautiful '84 for $800 just recently, and used L-2Ks pop up on Craig's List frequently and end up going for $1,000 or even less?