What are Major and Match penalties for?

Major penalty (Section 17). Four minutes, fully served. It is called if a player:

• commits a Minor penalty in a reckless, or an intentional and aggressive, manner (not intended to injure). A Major does not apply to Delay of Game, Illegal Substitution, Interference or Unsportsmanlike Conduct.
• engages in rough play, an act of unnecessary aggression not severe enough for a Match penalty (for example a single one-handed push into the face or a "face wash" with an open glove).
• commits boarding, body contact, charging, cross-checking or elbowing with initial contact to the head or from behind. If the official deems there was intent to injure, a Match penalty is assessed instead.

Match penalty (Section 18). Game ejection, suspension from the next game, and a teammate serves a Major penalty. It is called if a player or team staff member:

• commits a penalty infraction with intent to injure, or fights.
• intentionally spears, butt-ends or kicks an opponent.
• excessively abuses an on-ice official before, during or immediately after a game (for example intentionally touching, holding, pushing, striking, tripping, threatening or persisting after a Misconduct).
• intentionally leaves the penalty bench or players' bench during an altercation and becomes involved in it.
• commits a boarding, body contact, charging, cross-checking or elbowing infraction from behind that propels the opponent into the boards, post or crossbar so they cannot protect themselves.