I'm not sure where "too different" begins, but it's quite different in the US. The transition altitude is uniformly 18000 over the entire continental US. Airspace above that is Class A, IFR only. The vast majority of airspace below that is Class E, and there is definitely mixed IFR and VFR traffic at all altitudes; it seems to be working out okay so far. We have Class B around the largest airports, and then Class C and D around the medium and smaller ones. In B, C, D as is true everywhere radio contact and a transponder is required. Speed restrictions do apply under 10,000 and within the lateral boundary of Class B.
I dare say that a lot of VFR traffic that is going cross-country will ask for VFR advisories, and thus will get traffic point-outs, and my experience is that it's almost always granted. The rated pilots that I know will very often file IFR even on good days when they are on a cross-country mission in order to get the extra level of separation services and immediate help if the weather is sketchy.
Also, we don't use the terms QNE, QNH or QFE. It's just "Southwest 1542, descend and maintain one five thousand, Manchester altimeter 30.03" cleared to descend from the flight levels.
You will see the occasional US military field report a TAF with QNHnnnnINS (but they report it in inches as indicated by INS).