All three are fiberglass boards.
Usually the epoxy boards on the market are phenolic epoxy, the yellow kind, which is generally not used as a rigid circuit board substrate, but for electrical insulation purposes.
FR4 is a pure epoxy board according to the NEMA standard. The normal color should be dark green, which is the color of epoxy. There are also yellow ones. Generally speaking, yellow FR4 is called yellow material, and white (green) is called white material.
FR4 is more expensive than epoxy board, and the price of fiberglass board cannot be confirmed.
