Difference between Functional Testing and Implementational Testing Approach

Testing simply means an activity that is performed in software engineering to check whether actual result matches expected result or not and to ensure and confirm that there is no defect in software system i.e., Software system is defect-free. There are various types of testing of software that can be performed. Two of them are Functional testing approach to check performance or functionality of system and Implementational testing approach to check implementations of technical specifications. 1. Functional Testing Approach : The functional testing approach is basically a process that is used to verify that a system performs as per expectation or not when all of features are exercised by any other system or directly by a user or customer. In this, system is tested against all of functional requirements or specifications. It is basically a QA (Quality Assurance) technique or process. It is also a type of black-box testing. 2. Implementational Testing Approach : In the Implementation testing approach, testing is done by simply joining two to more modules that are logically related to each other. It is basically a sub-testing technique of integration testing that is used for integrating each of tested modules into a system by testing each of integrated parts.
Difference between Functional testing and Implementational testing approach :

Functional Testing Approach	Implementational Testing Approach
In Functional testing approach, overall functionality of system is checked without knowing implementational details.	In Implementational testing approach, internal structure is being known to tester who is going to test software.
Only Testers are allowed to perform Functional Testing.	Only Software Developers are allowed to perform Implementational Testing.
Implementation Knowledge is not required to carry out functional testing.	Implementation Knowledge is required to carry out implementational testing.
Black Box Testing can be done without knowledge or understanding of programming techniques.	White Box Testing can be done with help of knowledge or understanding of programming techniques.
This testing approach is applicable to higher levels of testing.	This testing approach is applicable to lower levels of testing like Unit testing, Integration testing.
This testing approach is based on Requirement Specifications documents.	This testing approach is based on Detail Design documents.