Polymorph Self: A spell allowing the user to take the shape of anything he desires, but he will not thereby acquire the combat abilities of the thing he has polymorphed himself to resemble. That is, while the user may turn himself into a dragon of some type, he will not gain the ability to fight and breathe, but he will be able to fly. Duration: 6 turns + the level of the Magic-User employing it.The polymorph spells obviously go together, especially since Polymorph Others references Polymorph Self. They are, however, different in effect. Both spells concentrate on the physical abilities inherent in the physical form. Mental changes are ruled out for both spells; compare this to the AD&D version of Polymorph Others, which has a chance of causing mental deterioration.
Polymorph Others: Unlike the spell to Polymorph Self, this spell lasts until it is dispelled. The spell gives all characteristics of the form of the creature, so a creature polymorphed into a dragon acquires all of the dragon's ability -- not necessarily mentality, however. Likewise, a troll polymorphed into a snail would have innate resistance to being stepped on and crushed by a normal man. Range: 6".
Polymorph Self specifically rules out combat abilities in addition to mental abilities. Basically, it's meant to provide a disguise, an alternative travel mode, and resistance to dangerous environments. It's also useful for trickery. The duration is actually in keeping with the duration of other physical effects, but keep in mind that if we stick to "turns are always 1-minute combat turns", this spell lasts a much shorter time than we are used to.
In contrast, Polymorph Others is presented as a permanent change of state, pre-combat range spell and needs no modifications to duration or range to fit my new scheme. The comment about a troll retaining innate resistance to being stepped on is a little confusing because of the way the spell description changed for AD&D. There, it's emphasized that a really tough creature should remain tough; but I don't think that was the original way the spell was interpreted. The troll in this example retains the magical nature of the troll (regeneration), making it difficult to kill merely by stepping on it. In other words, powers and abilities not tied to physical form do not change. Birds polymorphed into fish can no longer fly, dragons polymorphed into poodles can no longer breath fire.
This may lead to some tough rulings. If a human is polymorphed into a medusa, does the victim gain the ability to petrify viewers? That depends on whether the petrifaction is caused by the medusa's hideous appearance, or is an inherent magical (non-physical) effect.