Hi Vis windcheaters can be made from all Polyester, Polyester/Cotton or All Cotton. The most common are Polyester and Poly/Cotton, the all cotton products are more expensive and usually used in environments where you can not wear polyester, eg the electrical component industry (cotton is static neutral).
On this web site we use the term windcheater to indicate the material has a smooth outer finish. Fleece or Polar Fleece is used to indicate the material is “fluffy” and these tops are in the Hi Vis Polar Fleece section of the web site . (It can be confusing since some manufacturers refer to the windcheaters as fleecy)