Filtering is related to simplification – in that they both cut down the amount of information.
Filtering is about removing certain information you don’t deem is relevant for the reader, while simplification is about reshaping the same information so you get the same basic facts, but faster.
Here is a very basic example explaining the differences:
Statement: Johnny has two parents – his mother is called Joan. His father is called Peter.
Simplification: Johnny’s parents are Joan and Peter.
(The same information is all there, it just takes up less room)
Filtering: Johnny’s mother is called Joan.
(The information about his father has been removed)
Filtering should be combined with customisation to ensure that you keep the information that is needed by the end user.