American Broadcasting CompanyIn 1984, when Superman II premiered on television, 24 minutes were re-inserted into the film (17 minutes on ABC). Much of the extra footage was directed by Richard Donner. In the ABC-TV version, a U.S. "polar patrol" is shown picking up the three Kryptonians and Lex Luthor at the end of the film. Without this ending, it appears that Superman has let the Kryptonians die, though Superman has a strict code against killing and their deaths aren't necessary once they are depowered. On the other hand, the theatrical version's ending implies that Luthor is left stranded at the Fortress of Solitude, leaving the viewer to wonder how he got to prison in Superman IV: The Quest for Peace — that question was answered in the extended versions. The ending of the extended cuts also has Superman, with Lois standing beside him, destroying the Fortress of Solitude.

More specifically:

In the ABC-TV version, Superman passes a Concorde jet on his way to Paris. This is not in the video release and was actually an outtake from Superman: The Movie as a bridge between Superman saving Air Force One and his conversation with Jor-El after his first night.
At the end of the film, Clark Kent bumps into a large bald guy, which reminds him to go to the diner to face the obnoxious trucker who beat him up earlier.
Superman destroys the Fortress of Solitude.
The Phantom Zone villains land outside the Fortress of Solitude with Lex Luthor and Lois Lane, trying to figure out how to get in.
Extended scenes of the three Kryptonians invasion of the White House, with Zod using a gun and Non frightening a dog.
Superman cooks souffle using his heat vision, during dinner with Lois at the Fortress of Solitude.
Extended discussion between Zod and Ursa on the moon.
The three Kryptonian villains are arrested in the TV version.
Much of the added footage was later restored for the 2006 Superman II: The Richard Donner Cut.

Also, there were various edits due to content issues:

Much violence in the opening White House scene was left out.
Much of the bully's line in the bar ("I don't like your meat anyway!") was altered to "I don't like you anyway" as the original line was too sexually suggestive for ABC.
About 35 seconds of the "battle of Metropolis Road" (Superman flying over Metropolis River) was deleted.
Some language and profanity were re-dubbed.
[edit] Canadian versionDuring the 1980s, CFCF12 cable 11 screened an edition of Superman II that was differently edited to that to the one shown on in the United States on ABC. This particular version has only been screened once in Canada. The first Canadian broadcast of Superman II had an additional few seconds of dialogue as Luthor and Miss Tessmacher were stopped on a snow bank admiring the Fortress of Solitude. In the first U.S. broadcast (the same evening), the scene begins abruptly as Luthor starts the snow mobile immediately after the dialogue sequence.

Scenes seen in the Canadian version but not in the ABC version include:

A little girl watching the destruction of East Houston by the Kryptonians on TV.
Longer conversation between Lois and Superman after he destroys the Fortress of Solitude.
Lex Luthor taking Perry White's coffee during the Times Square battle.
Lex and Miss Tessmacher admiring the Fortress of Solitude.
Lex's negotiating with Superman after they leave the fortress is longer.
All the footage mentioned that had been added for various network telecasts were incorporated into an even longer cut of the film that aired in some countries in Europe (the other U.S./Canadian cuts were derived from this version). Prepared by the Salkinds' production company, it is this 146-minute version that some Superman fans remastered from the best-possible materials into a professionally-made "Restored International Cut" DVD for availability on one of the many Superman fan sites. However, such plans backfired when Warner Bros. threatened legal action against the bootleg release. The RIC, like the longer version of Superman, may still be found on Internet forums and in sci-fi conventions.