Sidney Crosby is a good example of a high profile player that has had multiple concussions. [1] The risk in hockey does not come from the fighting, those are less common than most people think, rather it comes from taking big hits that knock the person off balance and send them head first into the wall. I have been playing hockey the majority of my life and one of the first things that I can remember being taught was to keep your head up and never go head first into the boards.

Hockey helmets are different than a football helmet. For starters, the shell of a hockey helmet is much softer than that of a football helmet. This can help to attenuate some of the energy from a hit. The other huge difference is the mass of the helmet. Hockey helmets are light compared to a football helmet.

Another large difference between the sports is the rules covering head contact. While it is illegal in both sports to hit with your head, football tends to see a much higher rate of "incidental" contact. Hockey players are not taking hits to the head every play

[1] http://www.espn.com/blog/statsinfo/post/_/id/131681/sidney-c...

Edit: Minor Typos

There's currently a lawsuit alleging the NHL hid the risks to the players, much like the NFL lawsuit.

https://www.theguardian.com/sport/2017/apr/05/nhl-concussion...

And the rates of CTE in former NHL players aren't exactly low. 9 of 16 (albeit a small sample) showed signs of CTE.

http://www.espn.com/nhl/story/_/id/20498726/nhl-players-relu...