In
English, it has to be taken as a single expression, meaning "changing path, many unexpected curves or unexpected changes of direction".
I believe the
Persian expression has been incorporated into
Urdu as well, but only figuratively to indicate a state of mind: agitation, vexation, distress.
"turn" is a substantive in the English expression, it means a bend in the road, or a rotation in one's direction, in order to properly face said bend.
It can also have a positive sense, "a man of twists and turns" can be someone complicated, but also someone resourceful, one who can quickly adapt to changing circumstances.
For example, Odysseus in The Odyssey, is "a man of twists and turns". (
πολύτροπος: shifting, versatile
)
[Edited]
If you are asking what the difference is between "twisting" and "turning", the former gives an idea of contortion in relation to some main axis. the second simply indicates a rotating movement without such idea.
If you are asking what does "turn" add to the idea of "twist and turn", probably not much. Poetic English is fond of alliterations, and the repeated sound
t... t... is appealing to them.