What is the difference between Quick Filter, Normal filter and Context filter?

These describe three different things, which is partly why the question gets asked.

A normal filter restricts rows in the view. It exists on the Filters shelf and the reader cannot change it.

A quick filter is the same filter *exposed as a control*, so a reader can change its value. Right-click the pill and choose Show Filter. It is a visibility setting, not a different kind of filter.

A context filter is a normal filter promoted above the others. Tableau materialises a temporary table of the rows that pass it, and every subsequent filter and top-N rule operates on that subset.

So: normal versus quick is about who can change it; context is about *when* it is applied relative to everything else.