Testing policy means all types of testing or testing 
techniques(i.e.functional testing,sanity testing etc).

Testing methodology means white box and black box testing.

A test methodology, like any methodology, is a structured
list of activities that must be performed to ensure that all
objectives are satisfied. With regards to Testing, the
objectives are:
1. Test the system completely (100% Test Coverage)
2. Evaluate the overall quality of the system using test
results.
Therefore a test methodology are those activities that must
be performed to produce a fully tested system.

A test policy details the implementation of the test
methodology and takes governance, standards, best practices,
  and people into consideration.

Testing policy is what a particular company follows.
Testing methodology is a process in which the appln is to 
be proceeded