You can usually buy them in the same place at the store, but a foam board is thicker - like two pieces of poster board with a 1/4 inch of foam between them.

Your foam board has a foam core between two sheets of heavy paper? That's actually better than poster board (which is cardboard, with a smooth surface).

Your teacher won't care about the difference.

They are the same size. A form board is made of foam and is thicker. I prefer foam board because it is stronger and does not bend.

A foam board is made of foam, and a poster board is made of cardboard, but you can probably use either one.

I have to do a project in Spanish of a state and I needed a poster board but I got a foam board are they the same I can't get a posterboard my dad is working and my dad keeps all of my moms money :P are they the same size or no which is bigger or smaller