what’s going on here?
Seems to be correct. What did you expect to happen?
Thought the results would be the same?!
It depends on shape and uv structure of a surface. Can you attach your file?
Create/ApplyUV are absolutely not guaranteed to unroll things correctly, as that is not their purpose. With CreateUV, every surface (even a sphere) becomes a rectangle which represents the relative parametrization in U and in V. If your curved unrollable surface is not completely uniformly parametrized (most free form curves and their resulting surfaces are not), CreateUV will not give the same result as Unroll.
Below is an example, file attached. Turn on points for the two surfaces to see the difference.
CUV.3dm (283.9 KB)
yes, i rebuild my surface, reparametrized it and got the wished result. thx again