The difference is, when Japan snubs Airbus over the A380, Airbus will simply go and find some other customers.
No chance...
The 7E7 is an aircraft that is being designed with boeings future traffic predictions whereas the A380 has been designed for a totally different model.
If the japanese snub the 7E7 it will still go ahead. However, letting them build 35% of it does make it more attractive to them..its a simple business deal