With the advent of the Oracle card reference, the wording of many old cards has been updated to reflect more "modern" terms and mechanics. Here are three such cards from Arabian Nights.
Card text: If Rukh Egg goes to the graveyard, a Rukh--a 4/4 red flying creature--comes into play on your side at the end of that turn. Use a counter to represent Rukh. Rukh is treated exactly like a normal creature except that if it leaves play it is removed from the game entirely.
Oracle text: When Rukh Egg is put into a graveyard from play, put a 4/4 red Rukh creature token with flying into play at end of turn.
Aside from the "reminder text" (yes, it existed, albeit in a different form, even back then) about what a token is, the wording is functionally quite different. The phrase "from play" is missing, and it was originally thought to work like the card Compost does today, which triggers if a black card goes to play from anywhere--hand, in play, or library. Under the original wording, you could build a deck of 40 Rukh Eggs, and win by simply discarding one per turn once you had eight cards in hand. It wasn't until the release of Duelist #4 in 1995 that an official statement was made from the DCI clarifying that the Egg had to go to the graveyard from play in order to generate the token.
Card text: Put one chip on Cyclone each round during your upkeep, then pay for each chip or discard Cyclone. If not discarded, Cyclone immediately does 1 damage per chip to each player and each creature in play.
Oracle text: Cumulative upkeep (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay for each age counter on it.)
Whenever you pay Cyclone's cumulative upkeep, it deals damage equal to the number of age counters on Cyclone to each creature and player.
Cumulative upkeep proper did not debut until Ice Age, six set after the release of Arabian Nights. But because the sets were designed at the same time, it's not surprising to see this borrowed mechanic show up in a rougher form. Cyclone has cumulative upkeep exactly, except without the benefit of a keyword. The Oracle puts that keyword in, and the card becomes easier to understand.
Card text: Select a creature in play when Oubliette is cast. That creature is considered out of play as long as Oubliette is in play. Hence the creature cannot be the target of spells and cannot receive damage, use special powers, attack, or defend. All counters and enchantments on the creature remain but are also out of play. If Oubliette is removed, creature returns to play tapped.
Oracle text: When Oubliette comes into play, target creature phases out. That creature can't phase in as long as Oubliette remains in play.
When Oubliette leaves play, the creature phases in tapped.
Heaven forbid if a creature can't use special powers! But seriously… The intent of Oubliette was to remove a creature from the game "in tact," meaning that when it came back, it retained all of its counters and enchantments. Traditional means of removing something from the game (Sword to Plowshares) didn't allow for such behavior; local enchantments were put into the graveyard and the creature was never to be seen again.
Nine sets later, Mirage debuted phasing, which did what Oubliette spelled out in so many words. Phased-out creatures retain all their characteristics, but are not affected by anything happening "in-game." It is interesting to note that a creature trapped by Oubliette is not technically "removed from game" anymore, but is placed in the "phasing zone" (otherwise known as "phaseland"), and subsequently cannot be retrieved by Living Wish or Death Wish.