423 Employee Stock Purchase

[Holladay]

My wife has an stock option in her new company for a "Qualified" 423 component and or a NON- 423 option.

What are the differences? Taxation?

In my mind, qualified is like a 401k corporate plan that is pre-tax vs a Roth, post tax.

Or is it options as to when she can sell the options?

I have done some research, and can't figure it out in simple terms.

The CP Brain Trust will provide a clear answer.