I'm sure the definition may have changed but originally, Estaz (if you meant Estaz not ersatz) is a "chenille" made of 100% Mylar fibers that is VERY flashy.
Chenille in the traditional sense was originally made of cotton or wool, later Rayon and other synthetic fibers with a protruding pile.
Today there is "sparkle" chenille made of both materials and flashy 100% Mylar chenille not branded as Estaz.
That's the reason I sort my body materials by color, not type. To me it doesn't matter what you call it as long as it looks the way you want...