Fast services call only at Harrow-on-the-Hill, Wembley Park and Finchley Road between Moor Park and Baker Street. Semi-fast services call additionally at local stations north of Harrow-on-the-Hill. Slow services call everywhere north of Wembley Park. Peak services sometimes omit Wembley Park.
This arrangement was valid until December. Now, most services are slow.
In addition, stations south of Wembley Park were served by the Met until 1939. In the seven years before that, the Met served Stanmore; before that, I do not know where services from Neasden would have gone. This is because the Stanmore branch only opened in 1932 (from 1939 to 1979, it was part of the Bakerloo).