Uber offers varying levels of service. In the Washington Market, Uber offers the following:
Uber Black: This is basically Uber limousine. It is the most expensive level of Uber offered here. There is Uber SUV, which does cost more than the regular Uber Black, but it is really Uber Black with a larger vehicle to carry more passengers or more items. The vehicle carries an insurance policy that covers the transportation of passengers for compensation. Here, if the vehicle carries Maryland or District of Columbia plates, the driver is supposed to have a limousine driver licence. Virginia requires no special licence for a limousine driver. This was the first Uber that appeared here, as it was the first in many markets. Uber determines the rates for Uber Black/SUV
Uber Taxi: Uber offers this service only in certain markets. You use the Uber application to summon the same kind of taxicab that you would hail on the street or for which you would call by telephone. The driver holds a hack licence from the City. The vehicle has a licence from the City. It carries insurance that covers the transportation of passengers for compensation. You pay the usual cab rates. The Local Regulatory Authorities determine the rates. Uber charges the user a fee for this. Here, the fee is the same as that which the customer pays for calling a cab. It has cost extra to call a cab in Washington since the 1920s. Washington is unique amoung major North American Cities in its prescribing the charging for calling a cab. You pay for Uber Taxi through the application, just as you would any other Uber.
UberX: UberX is effectively "anyone can be a limousine/taxi driver". This is the lowest cost Uber service available here. You are summoning someone's private car to give you a ride. Uber determines the rates. The driver may or may not have a professional licence. The vehicle has no special licence. The vehicle carries a private car insurance policy that will not respond if the vehicle is involved in a collision while logged in to the Uber application. The exception to this is the situation where the driver has purchased a Rideshare Endorsement or a "hybrid policy" that will cover collisions while working. Uber tells the UberX driver that it provides a policy that covers you while actually transporting a passenger. This has been the source of much debate. There is an UberXL available, here, which is simply UberX, but with a SUV or minivan. It is something similar to the Uber Black/Uber SUV, but at the lowest price.
I do understand that Uber does offer other services in other markets.
There is something called Uber Pool, which involves multiple pick-ups and drops for a lower rate to the passenger. I do not know the whole story on it or how the driver gets paid. I do know that some users will request Uber Pool knowing full well that the driver may have to make additional stops, then complain when he does so and one-star him.
There is a service called Uber Luxe, which provides a Mercedes-Benz, Rolls-Royce or other high-end vehicle. I do know that it costs quite a bit of money. That is about all that I know about it.
There is something called Uber Select, but I do not know much about it.
I drive both Uber Taxi and UberX. I drive UberX only enough to stay in the game, as there is no money in it. Despite all the wailing and crying about Uber, I find still, that there is more money in the taxi.