Pearls are listed according to hole size.
A .8mm hole is considered large for a pearl. Most "regular" pearl hole sizes range from .25mm to .40mm. What does this mean for you? Versatility. You can use a thicker cord and get some interesting looks that you could not get with a smaller hole size.
The differences between the pearls above (TB1) and the ones below (PB73) are that the ones above have a slightly smaller hole (.8mm vs 1mm) and have some tiny blemishes.