Date based pricing means that today a ticket may be $100, tomorrow it may be $110, the next day $105. It is predictable and when making your plans, you know what your ticket will cost. The price may be different per day, but once it is set it remains the same no matter whether you buy tickets six months ahead or one month ahead.
Dynamic or flexible ticket pricing means the ticket price for any day can change at any minute based on how many tickets have been sold. It’s more like buying an airline ticket. The price at noon may be $100 for the day you want to visit, at 12:10 it may be $110, a week later it might be $125. You can’t budget ahead to buy tickets at a later date because you only know what the price is at this moment. The price could also go down if Disney sees not enough tickets are being sold for a specific date and they need to spread out the crowds. People are used to getting airline credits back when prices go down, but I don’t see Disney doing that.
I don’t see how they can do this kind of pricing for multi day tickets easily, but I can see them doing it for single day, single park tickets for sure.