“What’s the difference between a hockey game and a boxing match?” (joke)

Hockey is known for its fights, and a popular joke is:
 
Q: What’s the difference between a hockey game and a prize fight?
A: In a hockey game, the fights are real.
 
The joke has been cited in print since at least 1994.
 
“I went to a fight and a hockey game broke out” is another joke involving the two sports.
     
 
Wikipedia: Fighting in ice hockey
Fighting in ice hockey is an established tradition of the sport in North America, with a long history involving many levels of amateur and professional play and including some notable individual fights.
 
Fighting is usually performed by enforcers, or “goons”—players whose role it is to fight and intimidate—on a given team[2] and is governed by a complex system of unwritten rules that players, coaches, officials, and the media refer to as “the code”.[3][4] Some fights are spontaneous, while others are premeditated by the participants.[5] While officials tolerate fighting during hockey games, they impose a variety of penalties on players who engage in fights.
     
Google Groups: rec.humor
World Cup.
Bill Evans
6/16/94
(...)
Q: What’s the difference between a hockey game and a prize fight?
A: In a hockey game the fights are real.
 
Google Groups: alt.humor
Hockey
Keith E. Sullivan
9/1/97
(...)
What’s the difference between a hockey game and a prize fight?
In a hockey game, the fights are real.
 
Google Books
The Good Sports Joke Book
Compiled by Paul M. Miller
Uhrichsville, OH: Barbour Publishing
2004
Pg. 138:
Q, What’s the difference between a hockey game and a prize fight?
A: In a hockey game, the rights are real
 
Twitter
Joke of the Day
‏@jokeoftheday69
Q: What’s the difference between a hockey game and a boxing match?
A: In a hockey game, the fights are real.
#MadStrong
11:39 AM - 1 Jun 2015