For reference:
Official Card Reference:Sayge, 4 (Darkmoon Faire-2R)
Ally—Gnoll Fortuneteller, Unique, 4 [Melee] ATK / 4 Health
At the start of your turn, remove the top card of target opponent's deck from the game. If it's an ability, ally, or equipment card, you may play it this game. (Pay costs as normal.)
Touch of Chaos, 6, MaPrLo (Dark Portal-284R)
Weapon—Wand, Wand (1), 1 [Shadow] ATK, 1 Strike
When Touch of Chaos enters play, remove all ability cards in your graveyard from the game.
<p> At the start of your turn, choose at random one of the ability cards you removed this way and put it into your hand.
Sort Answer: They're worded differently.
Long Answer: Touch of Chaos has two triggered effects; one that triggers when it enters play and another that triggers at the start of your turn. Triggered effects can be identified by the use of the words "when" or "at".
The important thing to note here, is that Touch of Chaos has two different powers, while Sayge only has one power. Line breaks, noted by "<p>" in the OCR, signify the end of one power and the beginning of another. As such, we can tell that Touch of Chaos has two triggered power, since a power starting with the word "when" or "at" is always a triggered power. Triggered powers, by default, only trigger if the card it is on is in play. Some triggered powers work in other zones, but they will specifically state that they work in another zone, or will not make sense if they don't work in another zone.
So, Touch of Chaos has the triggered power "At the start of your turn, choose at random one of the ability cards you removed this way and put it into your hand." that will only trigger if Touch of Chaos is in play.
Sayge also has a triggered power that will only trigger if it is in play. However, Sayge's power also creates a continuous modifier that allows you to play the card that was removed. If a duration is not specified when a continuous modifier is created(ie. this turn, until the end of this turn, until the start of your next turn, etc.), then it will last for the remainder of the game. So, the effect of being able to play that card lasts until that game ends or until the card changes zones(since when a card changes zones it is considered to be a different card).
======================
Sweet Zombie Uther!
A guide to understanding flowcharts.