What is the difference between Morse taper and Jacobs taper?

What is the difference between Morse taper and Jacobs taper? Jacobs Tapers are used almost exclusively for Drill Chuck Mounting. Morse Tapers are found in a wide variey of tooling: drill bits, reamers, end mill holders, drill chuck arbors, collets, lathe centers, etc. morse taper on drill press chucks I just picked up an off shore floor stand drill press. Actually not a bad deal for $75. Its got a brand new 3/4 chuck on it,.marked JT-3 the nameplate on drill,says spindle is an MT-3 My other drill press (Delta/Rockwell made in USA) has a chuck I replaced with a 5/8 grizzly and is marked JT-33. Please explain why these seem to fit but are marked completely different. Google it. It will call out the dimensions, and they are not the same. MT3 Morse taper 3. This refers to the arbor that attaches to the chuck. The spindle of the drill press accepts a MT3 arbor rather than just having a JT33 or similar at the spindle to accept a chuck. The MT3 makes the drill press more versatile. The chuck fits on the arbor with a different type of taper. JT3 is a jacobs taper. There are a lot of different arbor tapers and chuck tapers so you would have to google to find any additional specs. The wikipedia entry for machine tapers lists dimensions for the various types, but the dimension charts aren’t consistently formatted for the different types, do it’s hard to cross reference the dimensions. If the drill was made in Asia, it’s fully possible the manufacturer listed the wrong taper on the drill, or chuck, because the fine points of the different standards sometimes get lost Overseas. Makita for instance, used Whitworth Nuts on their old grinders, but the wrenches supplied with the grinders were metric. The other possibility, is that the chuck has an internal recessed taper, rather than a fixed taper shaft, and the chucks internal taper is JT-3, and the drill also has an internal taper, which is the MT-3, And the manufacturer mounted the drill chuck on a JT-3 to MT-3 double tapered arbor yo mount the chuck on the drill.