2(8x^3 + y^3)(8x^3 - y^3)

Hmm .... the two similar terms can be further factored like this

(2x+y)*(4x^2-2xy+y^2) ==> 8x^3 - 4x^2y + 2xy^2 + 4x^2y - 2xy^2 + y^3 ==> 8x^3 + y^3

(2x-y)*(4x^2+2xy+y^2) ==> 8x^3 + 4x^2y + 2xy^2 - 4x^2y - 2xy^2 - y^3 ==> 8x^3 - y^3

So:

2(2x+y)*(4x^2-2xy+y^2)(2x-y)*(4x^2+2xy+y^2)