Aren't they really all the same program?

No, not really. Here are some ways they differ:

Adv. Placement

International Baccalaureate 

ACP Dual Credit

Is a university letter grade awarded and recorded for credit at the university?

 NO NO YES

Is the instructor required to have at least a master's degree?

 NO NO YES

Do classes provide a broad, subject-based curriculum?

 NO NO YES

Is "credit" awarded based on a single test score?

 YES YES NO

Is there direct accountability to national, state, and local educational authorities?

 NO NO YES

Is the program managed by an educational institution with national academic accreditation?

 NO NO YES
Is the program managed by corporate entities with no academic accreditation? YES YES NO

  

Want to know more? Visit Concurrent Enrollment: National Trends & Research (NACEP)