TG UK is absolutely scripted, just like the US version. They have learned to be free and easy with the lines, so it seems spontaneous. The US crew is still finding its theatrical "feet".
Another difference between the two shows is, mostly just your perception of it. Having watched the UK version first, the US version will seem like the musical equivelent of a "cover tune", and never make the same impression on your mind. You can't help but compare it to the original, so it never seems adequate, always clumsy.
The biggest difference to me, is that the UK version has that satirical British humor, that I grew to love from Monty Python. You can't recreate that, without it looking like a lame copy. The proverbial "die" can only be struck once. The US version needs to be different, or it will fail.
Jezza is always putting us down. I'd like to see something from Britain, that can do 7:22 or 7:26 on the Ring, has a rain worthy roof, wipers, etc, (not a Radical go-kart) for the same money. They always put some Italian, million dollar hyperexotic up on a pedestal for worship, but have nothing of their own. Instant karma *******.