but the first page for Durham does give you the University, Durham City Tourism, the Cathedral - all things that might make an inbound tourist think "that looks nice, I think I'll go there..." - the first page for Teesside doesn't i.e. the second entry is Wikipedia, which says:
Teesside is the name given to the conurbation in the North East of England made up of the towns of Middlesbrough, Stockton-on-Tees, Hartlepool, Redcar, Billingham and surrounding settlements. It was also the name of a county borough between 1968 and 1974. Teesside remains an important centre for heavy industry, although the number of people employed has declined.
Its inhabitants are increasingly referred to as "smoggies". Initially a derogatory term used by people from other parts of the North East region for Teessiders (due to the supposed smog in the air from the area's petrochemical industry), the moniker has in recent years been accepted by the people of Teesside as their own.
That should pull the punters in...
The point of changing the airport name was to raise its profile amongst inbound loco customers so they might come here rather then Prague or Dublin or Budapest and who might not know where Teesside was or what they would find when they got here, but had heard of Durham so might have a look.
Assumption would be that locals would be able to work out that Durham Tees Valley and Teesside were the same place
Not saying it's right, but that would be the thinking.