What is the difference between assembly language of x86 and x64 architecture?

Question

I am studying this book here . Now it says repeatedly to use a x86 processor cause its source code's are based on x86. But My laptop is of type amd64 . So I want to know how much is the difference. Can I continue reading the book and understand?

Answer 1

Actual 64 bit programs use a different instruction set (though it has a strong family resemblance). But that doesn't need to concern you, as it's backwards compatible: 32 bit code runs just fine, if you don't attempt to compile it as 64 bit code.