Testing is not a separate phase and carried out with as part of the iteration

Testing is a separate phase and carried out once the development is DONE.

Testers and developers work together

Tester work separately with developers

Testers are involved from the requirement phase so that they will be able to WRITE the test plan and acceptance criteria. Also, Logical Acceptance test cases would be ready along with requirements

Testers are not involved in the requirement phase.

Acceptance testing is done in each iteration and customer feedback is taken

Acceptance testing is done at the END of the project 

Every iteration completes its own testing thus ALLOWING regression testing also in each iteration in case of release of any new logic or functionality

Regression testing is done at the end of the development phase.

Continuous testing with test levels overlap

Testing is a timed activity and test levels cannot overlap

The entire team is responsible for the testing activity

Test Lead or Project manager leads this phase

Client involvement is needed throughout the phase

Client involvement is needed only at the requirement phase only.