It depends on your requirements, some examples that might help:
- Batch Export is missing from all but the full version
- Elements has less rack-based VST instrument slots and does not allow recording from busses
- Elements has only a single mixer
A feature comparison is available here for Cubase and Artist:
http://www.steinberg.net/en/products/cubase/whats_new/new_features_comparison.html
unfortunately there is no comparison with Elements, maybe some owners can comment.