I'm not the person you're replying to, but from a consumer point of view UberX feels like a limo service (in Paris, London..)

In London for example, if you didn't know anything about the company, you wouldn't know the UberX drivers were any different to more traditionally set-up private firms like Addison Lee. Whereas UberPop in Paris felt like getting a ride from an amateur.

Huh, that's interesting. Over here (Seattle), UberX feels more like Paris' UberPop (citizen drivers, their cars, however still some regulation by Uber) and UberBlack is the full on towncar service that's professionally licensed (and most of them run private car services on the side).

This varies depending on geography. In some cities UberX are regular citizen drivers, but in others UberX are professional drivers.

Here in New York all UberX cars, and their drivers, are licensed in the same category as black cars and limos.