As all others said, E roads and A roads are motorways. AP roads are toll motorways. This means that if you get to a junction and sign says, e.g.: Marbella AP-7 and Marbella A-7, that means that one is paying and the other is Free of charge.
When you see a raod like MA357, it´s a "provincial" road. (MA = Malalga or AS= Asturias). You may also found for isnt. in Asturias a road called LE-1, this is a a small road or path, that belongs to the local council ( Municipal), in this case, Concejo de Lena in Asturias. (To see those roads in MapSource you need to go to a very very close sacle, like 300 meters.).
In the REGION of Castilla-Leon, all main normal roads are C (=Castilla Leon) in Extremadrua Region: Ex, in Andalucia: A, But if in Málaga, that belongs to Andalcuia, you take a road named Ma-123, it´s a provincial road, normaly doble carriage.
So after all this story, if you wanna go fast: AP, A and E.
Have a nice drive..