Flybe ticket classes - K?
 

I'm looking to make a first flight on FlyBe (BAEC long termer), and my corporate booking system gives me the same trip twice, with different classes.

The first is for Just Fly, Get More and All In - and I can see those on the Flybe site.

I then get a second option, same flight, but says Economy (K) and Economy (U). All 5 of these flights have different prices.

Has any clever soul here go an idea what these K and U tickets are, given they don't match Just Fly and All In?

Thanks!