Difference between acceptance test and functional test?

Question

What is the real difference between acceptance tests and functional tests?

What are the highlights or aims of each? Everywhere I read they are ambiguously similar.

Answer 1

The relationship between the two: Acceptance test usually includes functional testing, but it may include additional tests. For example checking the labeling/documentation requirements.

Functional testing is when the product under test is placed into a test environment which can produce variety of stimulation (within the scope of the test) what the target environment typically produces or even beyond, while examining the response of the device under test.

For a physical product (not software) there are two major kind of Acceptance tests: design tests and manufacturing tests. Design tests typically use large number of product samples, which have passed manufacturing test. Different consumers may test the design different ways.

Acceptance tests are referred as verification when design is tested against product specification, and acceptance tests are referred as validation, when the product is placed in the consumer's real environment.