The characteristic of a straight staircase is that it has no bends or turns. In the case where the floor is very high, it may be necessary to add one or more rests in the stairwell.
A quarter-turn staircase has a quarter-circle shaped course based on a 90-degree turn. The steps around the bend can be straight or crooked. The quarter-turn staircase can swing at the bottom, top or middle, however, the stairs only swing once in the stairwell.
A half-turn staircase is often a staircase that is U-shaped. If there is a desire for one or more landings in the half-turn staircase, it will require both more space and width, which is why the depth of the rests can vary greatly.