Difference between courses and classes

Content

Hi,

we need to extract all the courses from our Taleo Learn Center. 

What we don't understand is the difference between courses and classes.
Are courses mapped 1 to 1 to classes? 

We have extracted all courses and all the classes but it seems that there are classes with a class name that does not match the course name and vice versa (there are courses for which we don't find a related class).

Could anyone provide an explanation of these 2 elements and to suggest an approach to extract all the courses from the application?

Regards,

Alberto