What's the difference? The primary difference is that the pro-dies have a dedicated die piece for the female vs male snap piece, which need to be switched out depending on which side of the snap you're installing. The no-change dies do not require switching dies.
Important! Professional-grade dies are available only for the KAM table presses. They do not fit the portable KX professional presses.
Most (not all) people who have used both versions seem to prefer the no-change dies. However, technically speaking, the professional-grade dies offer the utmost precision.