What are the advantages of eiach type of material used in a holster?  Which one is more comfortable than the other and why the slight price difference between horsehair and cowshide?

horsehide tough as nails and long wearing med cost
cowhide tough and more supple than horse most comfortable  lowest cost
sharkskin  toughest of all but hard on clothing high cost
take a look at the bladetech plastic holsters.  once i got one i had to have one for each of my guns.  i find them to be the most comfortable and best fit.

the slight price difference between horsehair and cowhide?  demand vs supply.  or your holster is made from "my friend flica".  i like horses.  they taist just like chicken.

 The most important thing to remember is that a sharkskin holster on your hip means one less shark that may be knocking on your door with a "candygram".

I use a lot of horsehide holsters from Kramer and Sparks.  They are much denser than cowhide and hold their shape better.  For example, my Kramer Belt Holsters have never colapsed and they have no reinforcement around the mouth.  Ive had that happen with cowhide holsters.  It also means if they are crushed they spring back into shape easier.  As if thats not enough, a horsehide holster can actually be thinner than cowhide and be stiffer.  Next to kydex, its my prefered holster material.