In term of construction, what's the difference between cheap vs. expensive power cables

When it comes to interconnects and speaker cables, it is easier to understand the justification for the costs of these cables.  But when it comes to power cables, it is a little difficult to understand.

Some believe that as long as the power cable has enough gauge the that's all you need.  I've used some cheap power cables vs. some high price cables and there are clearly differences in sound, so the "gauge" of the cables is not the ONLY thing and it's a little bit more complicated than that.  

In speaker cables design, you can adjust the R/L/C parameters to achieve a certain kind of sound and it's easy to visual how these parameters will affect the sound.  For example too much C then the sound will lack leading edge.  Too much L then the sound will be brittle.  If too much R then the sound will lack dynamic.  Or if the cable has too much jitter, then the transparency will be affected.

But the power cable main job is to establish a DC source, it's not too clear how the R/L/C parameters will affect the sound the same way these parameters will affect the sound of the speaker cable.  Also I am not sure how jitter would affect a power cable either

So the bottom line is what's actually inside a power cable that make them so expensive?  Do they use fancy dielectric?  How about construction geometry?  

For a designer, I mean how do you fine-tune your power cable.  How do you know your power cable will sound good?