TuneBoth numbers describe the same note: the A above middle C. They differ in where that A is placed.
How big is the difference?
432 Hz is 31.77 cents below 440 Hz, about a third of a semitone. Most listeners can hear it side by side, but not on its own.
Which is standard?
A = 440 Hz has been the international concert reference since the mid-20th century. Some orchestras tune slightly higher, to 442 or 443 Hz. A = 432 Hz is popular in some meditation and sound-healing communities.
What it means for singing bowls
Hand-made bowls are not cut to a reference pitch, so a bowl's note can fall anywhere between two semitones. The singing bowl tuner shows the deviation from both systems so you can describe a bowl honestly, for example “F4, 12 cents above A432 tuning”.
Claims you may read
You will find claims that 432 Hz has special healing properties. There is little scientific evidence for them. Choose the reference that suits your ensemble or your ears.