Although Alma briefly noted that there is repentance and the opportunity to stand clean before God, his emphasis is on the negative judgment, because that is what awaits the unrepentant people of Ammonihah. Alma has spent no time on the temporal death and resurrection, because that is simple. All receive the benefits of resurrection without condition.
The difference is that there is a second death. Alma defines that as a spiritual death rather than a physical death. By using the same term, however, he can more easily compare and contrast the temporal and spiritual deaths. Both can occur. The first is automatically overcome, but the second is conditionally overcome.
Alma explains that those who do not repent, who do not accept Christ’s name, will incur a final and complete separation from God. They will be under the “power and captivity of Satan.” In the black-and-white imagery that is often used in prophecy, there are only two options for the judgment, good or evil. Those who die the spiritual death have elected evil, and, hence, are subject to Satan, as the opposite of God.
The lake of fire and brimstone should not be seen as literal, but rather symbolic of the opposite conditions of living in the presence of God.
Modern Saints understand degrees of Glory and think about the question of whether there might be progression after entering those Glories. Those are not Alma’s concerns. His teaching shows only the two options. Once assigned to Satan’s domain, there is no change, as mankind does not die again in order to enable another change.
That should not suggest that there are no degrees of Glory, only that they were not the reason Alma preached this sermon. For this people, they had to choose repentance or destruction, and the destruction would be real. They really had only two choices: repent and survive, or remain unrepentant and be destroyed.