Tillotson:
A coworker of Winston's, Tillotson sits across from him in the Records Department and is extremely secretive about his work.
Ampleforth: A coworker of Winston's, and a poet who works in the Records Department rewriting politically or ideologically objectionable Oldspeak poems.
The point of view dictates our viewpoint into knowing things, whether that be from a third-person omnicscent to a first-person tell of tale. With your specific point of view comes things in detail for each kind.