Is there a difference between wide ruled notebook paper and A4 paper as far as size and/or dimensions?

I was looking online on how to make a "cootie catcher" and one of the websites that came up said that I need "A4" size paper. Is regular wide ruled notebook paper the same size/dimensions as A4 paper? If they aren't the same, can someone please give me some examples of what kind of paper would be considered A4 paper (for example, printer paper, etc.) Thanx very much (ahead of time) for taking the time to read this and/or answering this!