The fares prices themselves on that route are actually very similar. However, the rules and restrictions do vary a lot (e.g. UA's ZRSN50E fare is only valid "1NOV-30APR", while DL's IRATLAP has no seasonality restrictions):
[KVS Availability Tool 2.8.0/Platinum - Sabre: Fares/ZUJ/SG-USD]
Code:
LAS Las Vegas Mccarran Int'l NV US [KLAS]
LON London Metro UK = LHR LGW STN LTN LCY
RT Mar-Feb
Carrier From To Fare Cur Expiry Min Max Fare Basis
--------- ------ ---- --------- ---- --------- ---- ---- ----------
UA LAS LON 2872 USD 7 30 ZRSN50E
UA LAS LON 4794 USD Sun 12M ZLRSNG1E
UA LAS LON 4794 USD Sun 12M ZHRSNG1E
UA LAS LON 5258 USD Sun 12M ZRSN14E
UA LAS LON 7396 USD Sun 12M ZRSN21E
UA LAS LON 10639 USD CRGB
UA LAS LON 12766 USD C
[KVS Availability Tool 2.8.0/Platinum - Sabre: Fares/ZUJ/SG-USD]
Code:
LAS Las Vegas Mccarran Int'l NV US [KLAS]
LON London Metro UK = LHR LGW STN LTN LCY
RT Mar-Feb
Carrier From To Fare Cur Expiry Min Max Fare Basis
--------- ------ ---- --------- ---- --------- ---- ---- ----------
AA LAS LON 2872 USD 7 30 IRLEISE
AA LAS LON 2958 USD 7 30 IHGOSALE
AA LAS LON 2958 USD 7 30 IRGOSALE
AA LAS LON 4794 USD Sun 12M ILAPUS
AA LAS LON 4794 USD Sun 12M IHAPUS
AA LAS LON 5258 USD Sun 12M IR14GB
AA LAS LON 7430 USD Sun 12M IR21GB
AA LAS LON 10163 USD 12M JR
AA LAS LON 12766 USD J
[KVS Availability Tool 2.8.0/Platinum - Sabre: Fares/ZUJ/SG-USD]
Code:
LAS Las Vegas Mccarran Int'l NV US [KLAS]
LON London Metro UK = LHR LGW STN LTN LCY
RT Mar-Feb
Carrier From To Fare Cur Expiry Min Max Fare Basis
--------- ------ ---- --------- ---- --------- ---- ---- ----------
US LAS LON 2982 USD Sun ZG50XN
US LAS LON 2982 USD Sun ZG50XY
US LAS LON 5066 USD Sun ZG14XY
US LAS LON 7788 USD Sun ZG21XY
US LAS LON 9728 USD CG0RY
US LAS LON 11408 USD C
[KVS Availability Tool 2.8.0/Platinum - Sabre: Fares/ZUJ/SG-USD]
Code:
LAS Las Vegas Mccarran Int'l NV US [KLAS]
LON London Metro UK = LHR LGW STN LTN LCY
RT Mar-Feb
Carrier From To Fare Cur Expiry Min Max Fare Basis
--------- ------ ---- --------- ---- --------- ---- ---- ----------
DL LAS LON 2315 USD Sun 12M IRATLAP
DL LAS LON 2982 USD 7 30 IRLEISL
DL LAS LON 2982 USD Sun 30 IRHOLSL
DL LAS LON 5215 USD Sun IRA14GB
DL LAS LON 7540 USD DRA21GB
DL LAS LON 8953 USD JRUS
DL LAS LON 8953 USD DRUS
DL LAS LON 8953 USD IRUS
DL LAS LON 9367 USD CR
DL LAS LON 9367 USD JR
DL LAS LON 12884 USD J
DL LAS LON 12884 USD C