Would you please tell me what "placement" means in "Placement Tests" or "Advanced English Placement Courses"? How are they different from normal tests and normal advanced English courses?
Advanced Placement refers to the level of coursework that is appropriate for a student. The primary difference between an advanced course and an AP course is the opportunity to receive college credit for an AP course, based on performance on a standardized national exam, each year. Credit for AP courses is recognized by most colleges and universities in the US and many others around the world.
Edit: Of course, I'm assuming you are referring to the internationally recognized Advanced Placement courses and the testing program offered by Educational Testing Service (the same folks that offer the ACT, SAT, and TOEFL exams).
2nd Edit: Universities recognize these test results for college credit for courses offered in high schools. I don't believe I made that clear, above.