Significance of hand placement in forming mudra In Suzuki's "Zen Mind, Beginner's Mind" (online copy here), instruction is given on how to form the specific hand position (mudra) when meditating. He advocates "put[ting] your left hand on top of your right." This is the position I have been using in my short months of meditating, and is the position also taught to me at my local Zen center.

However, this resource, by Ven. Mahathera Nauyane Ariyadhamma, advocates the opposite: "back of the right hand over the palm of the left."

Question: why the difference? and, Does it even matter?
Short Answer: It doesn't matter.

Long Answer

Some postures are said to be more conducive to concentration, and perhaps this is true to a certain extent.  Perhaps there is something with certain hand placements which may help keep people a bit more focused (maybe the bare attention required to keep fingers barely touching, for instance). However, don't make too much of this.  Ultimately, how you sit is a means to help facilitate your concentration and mindfulness, unless you believe that your suffering in life can be solved by how you hold your hands.