Surprise, waylay, ambush are comparable when they mean to attack unawares.
Surprise is in military as well as in general use. As a technical term it implies strategy in the disposition and movement of troops and equipment and secrecy in the operations; it need not suggest that the attack has been successful.
In more general use one may surprise a person or something he is concealing by coming on him when he is off guard.
Waylay commonly suggests a lying in wait on a road or highway. Sometimes it implies concealment by the roadside and an often evil intent to disturb or interfere with (as by robbery or assault).
Sometimes it carries no suggestion of hostility or evil intent but implies intercepting a person in his progress and detaining him.
Ambush tends to evoke the image of would-be attackers concealed in a thicket; it is often used in reference to guerrilla warfare, but it can be extended to other situations in which one is caught as if by an ambush (see AMBUSH ).