They're all in the same cabin - economy. W is the lowest booking code I belwive, but all are able to calim FF miles on. The main difference between them will be the number of seats per flight they sell and the rules and restrictions on the tickets.
another difference is also (non) refundability of certain classes. you should read (or have your travel agent do so) the conditions, attached to each class. If you are Miles&More member, you'll only earn 50% of miles in W class on transatlantic segment
Those letters are only relevant for pricing your ticket.
Your seat and service are the same as everyone else in economy class.
It used to be generally the case that the further down the alphabet you went, the lower the ticket cost; making Z inventory your Bulk Fare tickets...the cheapest was to get transportation on that airliner. "A" class was used by some airlines for frequent flyer/free first class inventory.
The lower the alphabet, the lower the price policy is no longer the case.
Tired of airline bankruptcies....EA/PA/TW and finally DL.
You should also be aware that it is standard policy with tickets booked through United with those lower booking codes, even with pre-assigned seats, for fellow Star Alliance carriers SAS and Lufthansa to re-assign you seats in the back rows of their long-haul aircraft, which is particular distressing on A340/A330 with their narrower rear fuselage...
Quoting Rwylie77 (Reply 6): I am a UA Mileage Plus member, so do I get full miles on a W ticket?
yes, you do.
Also, a tip. If you have a Q fare ticket I believe you are also eligible for an upgrade. Go to EBAY and purchase a system wide upgrade from a premier who isn't using theirs or are willing to sell them. I saw some the other day for $99.00 OW, and that isn't bad.
If you do it, make sure it is a system wide not a regional.
There are different fares available to the public, w and v are no frill, dirt cheap, Q is starting its way up the ladder, so if the company is buying your ticket, and you care about comfort, go get a couple system wides and really enjoy your United Ride.