The difference between skyjack and hijacking is that “skyjack” is to steal or commandeer an airplane, usually by threat of violence to the passengers and “hijacking” is present participle of hijack.
The difference between somersault and flip is that “somersault” is starting on one’s feet, an instance of rotating one’s body 360 degree while airborne or on the ground, with one’s feet going over one’s head and “flip” is a maneuver which rotates an object end over end.
The difference between glad and gladden is that “glad” is pleased, happy, gratified and “gladden” is to cause to become more glad.
The difference between fluid and velocity is that “fluid” is any substance which can flow with relative ease, tends to assume the shape of its container, and obeys Bernoulli’s principle; a liquid, gas or plasma and “velocity” is a vector quantity that denotes the rate of change of position with respect to time, or a speed with the directional component.
The difference between seeder and drill is that “seeder” is a device used to plant seeds; a seed drill and “drill” is to create by removing material with a drill.
The difference between bill and fracture is that “bill” is any of various bladed or pointed hand weapons, originally designating an Anglo-Saxon sword, and later a weapon of infantry, especially in the 14th and 15th centuries, commonly consisting of a broad, heavy, double-edged, hook-shaped blade, with a short pike at the back and another at the top, attached to the end of a long staff and “fracture” is an instance of breaking, a place where something has broken.
The difference between efficiency and unbreaking is that “efficiency” is the extent to which time is well used for the intended task and “unbreaking” is present participle of unbreak.
The difference between uncountable and non-count is that “uncountable” is so many as to be incapable of being counted and “non-count” is uncountable.
The difference between hearsay and witnesses is that “hearsay” is information that was heard by one person about another that cannot be adequately substantiated and “witnesses” is attestation of a fact or event; testimony.
The difference between meatus and conchae is that “meatus” is a tubular opening or passage in the body and “conchae” is any shell-shaped structure.