A half-turn stair reverses direction through 180° around a half-landing. Solve the two parallel flights, the landing, and the stairwell footprint.
A half-turn staircase doubles back on itself through 180 degrees, with the two flights running parallel and a half-landing connecting them. It is the same configuration commonly called a U-shaped stair.
Yes. Both describe a staircase that reverses 180 degrees around a landing, with parallel flights.
It gives the most compact floor footprint for a given rise.
They are essentially the same 180° reversal; the terms differ by context.