What is the difference between laminar (LS) and turbulent separation (TS) for a flow over circular cylinder?

If it's any help try Dimples on Golf Balls for an explanation of laminar and turbulent boundary layer separation over a sphere - I think you'll find the reasoning similar to the flow over a cylinder.

What difference do you want to know about?

The turbulent one will have a smaller wake, this is why skaters use strips on their arms (streamlined shapes like cycling helmets are not allowed for them).

Thanks. In one paper by Trevin et. al, he talks about LS (laminar separation) and TS (turbulent separation) at Re=140000. How can we get laminar or turbulent separation using the same code?

First of all, I suppose your code is 2D.

Does it have a transition model?

My code is 3D DES using S-A turbulence model.

Ooh, isn't that a bit heavy for cylinder flow? Why don't you use a 2D solver? You run in fully turbulent then I suppose?

Anyway, if you only want to see the difference in the wake for engineering purposes, I think it's tabulated somewhere, maybe in the drag book by Hoerner.