I'd say it's more like comparing an F-14 to an F-15, they're both large fighters (mecha) but, have different aerodynamics (appearance) and load out.
Well, that's what it says in the manual. They used Stylet as a base and added extra thrusters so that it can hover in air and gave it a sniper rifle for long range attacks. Same base unit, just different equipment. (Kinda like a M14 and a MK14)