Strathmore Bristol Boards provides a stiff, strong surface to work on without the need for mounting, smooth and vellum surfaces available. Bristol Smooth has a flat, smooth surface and is great for pen & ink, mechanical pencil, airbrush, and marker.
Bristol Vellum has a medium surface with peaks and valleys, making it great for graphite, coloured pencil, charcoal, pastel, and crayons.

Bristol generally describes drawing paper that is pasted together to form multi-ply sheets.

Illustration board has 100% cotton drawing paper mounted on both sides of heavyweight board

VIDEO: What is the difference between Bristol Smooth and Bristol Vellum?