Arrow tracks and Vekoma tracks

In the 80's, Vekoma's tracks looked exactly the same as arrow's (except the section where rails joining together).

In the early 90's,  why did arrow changed the track ties from Vekoma's style to their own rounded track ties?

Well, originally, Vekoma designed their track like Arrows with their permission, and they would buy Arrow trains and running stock. I am not sure how much of the design Vekoma owns now, but it was indeed Arrows concept. As for Arrows newer track design, which is a little more curvy than their older stuff, I think its an easier design to bend and weld rather than their old track format.

Take a look at Deja Vu the track is completely different on it, the trains are suspended iside the track instead of outside.