A surface of revolution (about the Y axis) defined by a set of curves would be meshed with SHELL208 elements.
Both SHELL208 and SHELL61 elements are limited to axisymmetric models. Both elements must be defined in the global X-Y plane and the nodes must have positive X coordinate values.
SHELL61 assumes a linear elastic material and cannot be used with the large deflection option.
SHELL208 can do large strain, transverse shear deformation, hyperelasticity, plasticity and model composite layers.
The feature that the linear SHELL61 element has that SHELL208 does not is axisymmetric-harmonic applications such as a surface of revolution subjected to a horizontal earthquake. However, SHELL61 is a legacy element and if you have this application, Ansys recommends the general axisymmetric elements instead such as SOLID272.