Should I Buy a Running Shoe or a Trainer?

Running and Training seem similar. However, the two activities are different, as are the demands they place on your feet and your footwear.

Also, see What Type of Shoe Is Right For Me?

Running shoes:

Generally have more cushioning in the heel–the point of impact–and less protection through the ball of the foot
The amount of heat generated in the running motion is greater, so running shoes also are made with a higher amount of mesh to keep feet cool during exercise
Running, requires the support of at least two to three times your body weight, and each stride has moments with neither foot on the ground
With each step, the outer heel absorbs most of the impact before distributing weight through the foot in an S motion through toe-off
What does this mean to your shoes? Basically, it's the old axiom of having the right tool for the job

Trainers:

Generally, offer additional ankle support for both forward and lateral movement
Designed expressly for the gym enthusiast, with a seamless transition from jogging on a treadmill, lifting weights or doing step aerobics
While not intended for use in long races (ie, half marathons and marathons), shoes in our training category can be used in shorter runs (ie, mile races and 5Ks)