A pastry is totally different from a cake in terms of recipe, looks, taste just everything. Common pastry dishes include pies, tarts, quiches and pasties. I started with examples so it is kind of easy to explain.A pastry dough basically has flour and fat in the solid form. You can read more about it in my Mango Tart post. Just because you used butter for making your cake; does not make it a pastry. Or just because you made some clean square or rectangle slices you cannot call it a pastry. Even the famous Opera Cake which is sliced and served in a beautiful rectangle slice with amazing different layers is not called a pastry right!! So to answer your query No a pineapple cake and pineapple pastry is not the same thing.