Answer:
 Test Plan:

 It is a document that collects and organizes test cases by
functional areas and/or types of testing in a form that can
be presented to the other teams and/or customer.It is the
documented approach to testing. 

The tester prepares test Plan 

Test Strategy:

It is a document that describes the test efforts, test
configuration, testing tools to be employed, test
environments, exit criteria and entry criteria for testing,
what different types of testing will be carried out (for
example, smoke test, regression, load test, functional test
and so on)

 The Test Manager or Lead writes it. (Remember, the Tester
does NOT write Test Strategy. A Tester writes Test Plans and
Test Cases)

 Both are important pieces of Quality Assurance processes
since they help communicate the test approach scope and
ensure test coverage while improving the efficiency of the
testing effort.

Test Plan : 

A document describing the scope of testing, apporach, 
resource and schedule of intended test activities. 


Test Strategy: 
It is a policy of an organization that can be defined as a 
high level statment of principle that is used to govern set 
of activities in that organization. 

The test strategies also provide high-level guidance as to 
how testing is tobedone inthe organization.