I have a ticket booked CKG-PVG next week. I originally booked a ticket in F but the flight was cancelled. There is a flight I have rebooked in C. I'm wondering what the difference is if any between booking in F v C on this routing? It appears that F fares are booked into a 2-class 737 while C fares into a 2-class 738. That's the only difference I can find online. The price is $4 different. Both fares are refundable. So why the different class of service and does it mean it will be any different in any way? Does one have lounge access the other not?? One have a meal the other not??

FWIW The ticket agent could not explain anything about the difference to me. She wanted me to sign a 'voluntary downgrade' form that was a piece of paper saying I was giving up any right to any refund, even though they cancelled the original flight and both fares were fully refundable. She ended up directing me to cancel my original flight online (saying she could not do it on the phone) and I rebooked a completely new ticket. I'm assuming this kind of idiotic discussion (which took place over 3 days, 2 phones calls and one email) is par for the course with Chinese airlines but it seemed woefully inefficient.