From a language specific viewpoint I cannot say but from what I know the differences are the same as any OO vs non-OO language. OO cobol provides support for class and objects by providing the syntax and API's required to manage those.
Structured cobol supports function orientation with support for local variables (something standard cobol doesn't).
You can also say that.
In structured programing methode we first looks at the
function and will code according to the function.
In object oriented programing methode we first identifies
the objects (variables) and codes according to that.