Presidential proclamation: No force of law. Sign an international treaty! Hold a press conference and announce a new alliance! Nope. NONE of it is binding without Senate ratification. ie Law of the Sea Treaty, signed but not ratified. US is NOT a member of UNCLOS.
Executive Order: Orders the administration to form regulations and carry out actions, mostly domestic. Can be over-turned by judicial injunction, otherwise it's kind of an imperial mandate for unilateral administrative action.