I’ve done both Contiki (NZ, USA, Canada, Europe, Scandinavia, Peru) and Topdeck (USA, Canada, Australia). I did the Contiki USA Wild Western trip in 2014 and the Topdeck USA & Canada Adventure trip in 2016.
The USA & Canada Adventure was run on behalf of Topdeck, but was for all intents and purposes a Topdeck tour. Both the bus driver and tour manager were great. They did say who they worked for, but I can’t remember it now (and I didn’t note it in my notes). The tour was enjoyable and run just as well as the “real” Topdeck tour I did in Aussie last year. My understanding was that Topdeck was working towards running the North American tours themselves, they might be by now. Too much existing competition when they tried to enter the market themselves or something like that was the reason I was told for them not running the tours directly themselves.
I don’t drink and don’t really enjoy loud crowded places so I tend to ignore/not notice the going out drinking aspect of tours. Having said that, yes, thinking back there was a lot more drinking on the Contiki tours I’ve been on vs the Topdeck trips. But you don’t have to go out drinking and I certainly didn’t feel pressured to at all. In many circumstances the people that just wanted to go back to the hotel after an included dinner out were catered for better as the bus would drop them back at the hotel but the people going/staying out had to make their own way back.