what does it mean when it gives you the option of getting a internal or external waste gate for a turbo is it both the same, does it matter someone explain?

 

http://www.streetracersonline.com/ar.../wastegate.php

http://en.wikipedia.org/wiki/Wastegate

An external wastegate is a separate self-contained mechanism typically used with turbochargers that do not have internal wastegates. An external wastegate requires a specially constructed turbo manifold with a dedicated runner going to the wastegate. External wastegates are commonly used for regulating boost levels more precisely than internal wastegates in high power applications, where high (over 20 psi) boost levels can be achieved.

Below is a dual-turbo diagram with internal wastegates. You can see how the internal wastegate allows some of the exhaust to bypass the turbine to prevent "over-revving" the turbo beyond the desired pressure.

 

And here is a great picture of a turbo with an external wastegate.