Ursa Major is a "constellation" in the "northern sky" which is also called the great bear. Ancient people people saw this set of starsshaped as bear thus named it as big bear. It is visible for most of the year and from almost the whole world.
"Ursa Major" was used a lot as a "navigational tool" by sailors and travelers who used it to find North before compasses were invented. It is also called the big dipper. The "Big Dipper" is simply a "random pattern" in the sky that is easy to find, but it is only part of the "Ursa Major constellation" which is shaped like a bear.
