I'm not exactly sure. I see both at the grocery store: almond paste and then marzipan.
I buy the almond paste quite often and make the absolutely best almond bread!! It makes mini loaves and I give them as gifts at christmas time. EVERYONE wants the recipe. It is such a hit!!
So, since both of these are side by side at my grocery store made by the same company I tend to say they aren't the same.