I have a full Y fare change-of-station entitlement ticket (worth around $4,000) that I'm looking to change because of a personal travel preference. The key is that I'd like to keep the ticket fully refundable at least until my plans are nailed down. The route that I'm looking at (MSP-OSL-MSP) also has both changeable/refundable B fares (around $3,700) in addition to full Y fares ($4,800).

Looking at the B fare rules for this particular routing, it appears that there aren't any change or refund fees. Am right then to understand that nothing would stop me from potentially changing it again to a V fare (paired with some GUCs) or Z fare in the coming months if my plans firm up?

Is there any other substantive difference that I'm missing between B and Y for the change scenario listed above? Or are they functionally the same thing with an $1,100 price difference?