Not clear what distinction you are trying to make. They practiced mindfulness meditation according to a specific, published plan, and brain anatomy changes were noted. It doesn't seem they are making any claim other than, this series of exercises produce this effect.

The paper doesn't seem to be available, but the abstract at the author's page[0] says "Healthy but stressed individuals are randomized to either a meditation-based stress reduction intervention or health education control intervention."

[0]https://connects.catalyst.harvard.edu/Profiles/display/Perso...