What’s the difference between a Jewish sheitel and a regular wig?

Basically a sheitel is just another word used by some groups of Jews predominantly Orthodox Jews to describe the wig. So sheitel is synonymous with the wig. Orthodox women do not show their hair in public after their wedding. With a headscarf or a wig – referred to in Yiddish as a sheitel – they signal to their surroundings that they are married and that they comply with traditional notions of propriety. Many modern Orthodox Jewish women are continuing the tradition of covering their hair with wigs after marriage. The wigs they use are called a "Sheitel" which in Yiddish is a wig or half-wig. 

Why do Jewish women wear wigs in the first place?

The reason for this is to conform with the requirement of Jewish biblical law to cover their hair after they are married. They are not only signaling to others as well as providing a constant reminder to themselves that they are married by wearing a Kosher wig, but they are also attaining modesty in the process. Today, many wigs used by Jewish women come with a Hechsher (kosher certification) in order to ensure that the hair on the wigs do not originate from rituals deemed to be idolatrous. This is after it was revealed in 2004 that the hair from a number of Sheitel wigs came from Hindu women during a religious purification ceremony which is against Jewish biblical law.

Quality and material are the major differences. A sheitel must come from hair that sourced directly from verified distributors, who have a good reputation for ethically sourcing quality human hair. With the most experienced handicraftsman and the best hair, which make sheitel wig a extra quality wig. Based on research in Jewish wig salons in Britain and the United States and on Jewish online forums, internet discussions and blogs with a wider geographic reach, this article sets out to show the complex web of material, social, emotional, aesthetic and moral concerns that cluster around the sheitel and to highlight the role of the sheitel macher (wig stylist) in managing these anxieties and expectations. With good care, a sheitel could last up to a few years. 

In short, sheitel wig is a wig which is worn by some married Jewish women, that's why there are someone call it Jewish wigs, or kosher wigs.