While there isn’t a drastic difference between Olympic men’s ice hockey and the NHL, casual fans are almost certainly going to take notice in a few different rules. They might also notice the lack of fighting in the international game.
Though today’s NHL doesn’t come close to the level of fighting seen in the days of the 1980s enforcers, it’s still a thing that happens in the NHL. A dirty hit, targeting a star player or just ill will between competitors can all lead to a fight breaking out. But really, the NHL’s tolerance of fighting is the exception across the global hockey community rather than the rule, and Olympic hockey strictly prohibits fights.
According to international hockey rules, if a fight breaks out, it’s an automatic match penalty (an ejection and additional five-minute major). Plus, you always run the risk of a suspension or additional discipline against violating teams — it’s simply not worth the risk with so much on the line. Via the IIHF:
“Fighting” is not part of international ice hockey’s DNA. Players who willingly participate in a “brawl / fight”, so-called “willing combatants”, shall be penalized accordingly by the Referee(s) and may be ejected from the game. Further Supplementary Discipline may be imposed. A “fight” shall be deemed to have occurred when at least one (1) Player punches or attempts to punch an opponent repeatedly or when two (2) Players wrestle in such a manner as to make it difficult for the Linespersons to intervene and separate the combatants.
Any Player who persists in continuing or attempting to continue a “fight or altercation” after they have been ordered by the Referee to stop, or who resists a Linesperson in the discharge of their duties shall, at the discretion of the Referee, incur at least a Major Penalty (“Fighting”) plus a Game Misconduct Penalty (5’+GMP) in addition to any additional penalties imposed.
With NHL players missing the Beijing Olympics, it likely won’t be a huge adjustment for the participating athletes. They’re used to similar rules in college hockey and European professional leagues.
But fans shouldn’t tune in expecting to see any players drop gloves and throw punches. It’s just not part of the Olympic game.