How they're the same
Both eye pillows are a fabric filled with something, to allow them to conform to the shape of your face, effectively block out light, and apply a cool pressure. Both can also be put into the freezer if you want to increase the cool feeling on your face.
How they're different
The biggest difference comes in the "filling". The IMAK eye pillow is filled with tiny plastic beads with a smooth coating, to allow them to glide over your face and conform easily to the shape. One advantage is that it can be easily hand washed.
The IMAK eye pillow has a contoured shape, but to me this doesn't make much of a difference because either way they conform very well to the shape of your face.
One other thing to look at when considering an eye pillow is the strap. I've tried one with a strap and without, and I find I very rarely use it. I'd rather have something sitting there while I lie on my back, than have it strapped to my head. There may be times you would want it. But if you get one without, you can sew one on that actually fits your head. Or you could remove it if it was in the way. So I wouldn't call it a big selling point.
The IMAK eye pillow is cotton, and the flax eye pillow is made of silk.
So what do you use?
You may have guessed by now, I personally use a silk flax eye pillow. But either one will soothe your sore eyes and your headache. The advantages are tremendous. For a migraineur, the fabulous way these block out the light is worth the purchase alone. For me, the cooling effect does a lot to take the pain out of my eyes and the area around my eyes. If I have a bad headache attack, it's easy to stick the eye pillow in the freezer for an hour or two before bed. Then just putting it on for 15-20 minutes can cool the heat and make sleep a lot better.
Where can I get them?
Various kinds of eye pillows may be found at your local drug store. If you're interested in the specific brands discussed here, click the links below for more information. I've also found a good flax seed eye pillow with no added scent, and another great idea - an eye pillow with a buckwheat neck pillow to support and cool the back of your head and neck.