When we talk about electricity and cables, we talk about resistance , capacitance and inductance. Pardon my English. :)
Cable capacity or inductance can differ 10X even. For example, If one cable has 3X bigger capacity then the other, it will sound differently (the current flow will be different using simple words). That’s obvious and clear for everybody I hope. Cables capacity or inductance or resistance depends on materials used for construction (metal, insulator etc.), geometry of the cable. This is the reason why power cables and in general cables sound so differently. There are other factors like vibrations, RF.... that affect cable performance and it depends how well a cable is constructed and that is reflected in price.
Signal in power cables is not only 50/60Hz but many other frequencies superimposed that are "smuggled" into the system and contaminate the sound.
Some cables filtrate, attenuate RF by their geometry...
Price tag... hm... more expensive cables are usually better constructed, better materials, better geometry applied and so on. Generally, cables are way overpriced...There are not so expensive cables sounding very good (Lessloss, for example. Louis should buy me a beer :) ) and very expensive cables that suck. Cables are also system dependent and most important..... listener dependent. Listeners preference...... :)