Vexorg
I think irishguy28 has given you all the possible explanations it is possible to give you at that stage. There are plenty of conditions applicable to each fare letter, depending on the whole fare structure and the point of sale. The only thing we can say for sure is the higher you go in the fare code hierarchy (e.g. from Z to J in business class, from A to W in PE class and from let's say N to Y in Eco class), the more expensive it gets, the more flexibility you have in term of cancellation, modifications, advance purchase and minimum stay requirements.
I'd like to give you another hint : I think it was last year, I remember very well a thread you started complaining that you were earning only 25% of FB miles in your long-haul travels for work. It meant that you were booked in one of the lowest (and normally most restricted) Eco fares. But, you explained us in that thread that your tickets were flexible and refundable IIRC. So it means that your corporate fare has some special conditions for let's say a N or V fare, while if you book a N or V fare on AF or KL website (at a public fare), those tickets will not be changeable or cancellable (or with some high fees).

Who said that ???