The only real difference is they seem to have lasted longer from the ITV companies, the 'Bullseye adapted for Channel 4' skit dates from 1983
Was that Bullseye skit recorded like that? I've seen comments saying it was longer. The clip that keeps popping up on YouTube looks like it has been cut down.
It was presented that way in the original video (hence the end of part caption, which references its position in the tape).
I wonder if it was deliberate to present the Bullseye skit in the way it was, after all the voiceover said it was "adapted for Channel 4" and so as a mockumentary drive the entire thing downhill in terms of presentation and production compared to the regular programme. I suspect it worked on more than one level.
Rainbow Twangers was IIRC presented as the pilot for Rainbow, but of course what everybody would have forgotten at the time was that Geoffrey Hayes wasn't with the programme from the off, he was a replacement for whoever the original chap was.
Steve in Pudsey gave kudos