How is the mental practice of zen meditation different than mindfulness

I’m not all that knowledgable about mindfulness/Vipassana, beyond some casual reading about it. My lifelong practice has been Zen. There seems to be a lot of overlap between Vipassana and the Zen practice of shikantaza (“just sitting”), and thought-labeling as taught by Charlotte Joko Beck. The biggest difference I can see is between Vipassana and koan practice.

For comparison, I recommend the books Wherever You Go, There You Are by Jon Kabat-Zinn andTaking the Path of Zen by Robert Aitken. Th...