http://www.parcconline.org/assessment-blueprints-test-specs
Under most circumstances I'd stick to academic content standards and not use assessment blueprints, but there are exceptions. In the case of PARCC, it's helpful to get some guidance to what high school content might be addressed at Algebra 1 vs Geometry vs Algebra 2, since the Common Core standards themselves don't exactly specify what to expect at each high school grade level.
Under most circumstances I'd stick to academic content standards and not use assessment blueprints, but there are exceptions. In the case of PARCC, it's helpful to get some guidance to what high school content might be addressed at Algebra 1 vs Geometry vs Algebra 2, since the Common Core standards themselves don't exactly specify what to expect at each high school grade level.