Erik Kostson
Ansys Employee

Buckling - one is the linear buckling solver/analysis, and the other is doing an nonlinear analysis (large deflections/geometric nonlinear + material nonlin.) to find the buckling load.

I would recommend to look at our linear buckling course (uses the linear eigenvalue buckling solver):

For nonlinear buckling you can search and also the forum here has many posts on that.

Material to look at:
FInally there are many good discussions about these topics (search on the internet):

All the best