What are the differences between Tiagra and 105/Ultegra chainrings There is quite a big price difference between Tiagra and 105/Ultegra chainrings. Do the more expensive ones last longer? Is there difference between performance? Is the weight only relevant difference?

For what it's worth, all my current components are Tiagra (triple/10).
For most people, they're just a bit pricier. The weight difference is insignificant for almost everyone (excluding possibly serious racers). 

As for durability, I'd expect its more of a function of maintenance rather than trim level. But I'd actually guess the "lower end" Tiagra part is probably a bit more durable since its probably got a bit more material on it.