I recently participated in a conference. Several workshops were organized in parallel with the conference, and I also took part in one workshop to see what kind of material is presented there.
To me, there was no major difference between the conference paper presentations and the workshop paper presentations. Both usually discuss work that is in progress, i.e. could benefit from some new ideas. I didn't see a huge quality difference between workshop paper presentations and conference paper presentations. Both conference papers and workshop papers presented interesting ideas that usually had some merit.
My understanding is that the workshop papers are also peer-reviewed and additionally will be published in conference proceedings. So no difference here, either. Also, in both cases, questions and occasionally even some criticism were raised by the audience.
So, what is the difference in practice between workshop papers and conference papers?
Related question, not exactly the same: What is the point in publishing a paper in a workshop rather than in a conference?