The Physics of Electricity

There are differences that can matter mainly shielding from noise,  ability to establish a sound electrical contact on both ends and ability to deliver current when needed.    None of this is rocket science and requires  just a good quality power cord designed to do the  job well which has some cost but need not cost a fortune.  Current delivery will in practice matter more for power amps whereas shielding and ability to make a good contact may matter more in general.  

Wires are like ice cream. They come in all different flavors. The good ones are the ones that sound best in your system. Cost is not an effective determiner of end performance. Great sounding wires might cost just a few dollars or thousands.

One feature that clearly matters in many cases is whether the wire is shielded or not. Unshielded wires can pick up noise from nearby electronic devices more easily. Digital devices, switching amps, and power amps or other household devices with large power transformers and RF noise from radio waves are the common sources. LOw level signals like that from MC or even MM phono carts are most susceptible, though line level sources including the signal from pre-amp to power amp can be affected in a quite negative manner that may or may not be apparent from listening by these kinds of EM and RF fields.

I also tend to like wires with network devices that attempt to maintain constant electric properties like impedance by design regardless of length, etc.

It gets a lot greyer after these few things to me.....

DNM reson ICs are inexpensive, simple, and golden in my estimation however are not the best choice in some applications where a shielded wire is called for.

Even teh inexpensive networked ICs from MIT are very good. These are also shielded I believe.