{ 1 } - the theodicy tells us what God's reason for permitting evil is, while the defense only tells us what God's reason might possibly be.
{ 2 } - the theodicy tries to explain the suffering of animals as resulting from the sin of Adam and Eve, or perhaps the sin of Satan and the demons.
{ 3 } - There's no difference.

Plantinga says that, to refute objections to belief in God, we need only the latter. We don't have to claim to know exactly why God permits evil. We only have to give a possible reason.

In general, it's wise to appeal to premises that say as little as possible and yet still suffice to establish our conclusion. That way our premises are less likely to be refuted.