What is the difference between immediate judgment after death and the final judgment, according to Catholicism? According to this site, adapted from the United States Catechism for Adults,
&quot;Our Church teaches that immediately after death, our soul separates from our earthly body and we stand before God for judgement. We then enter heaven, Purgatory or hell.&quot;
but then
&quot;At the end of time, our Lord will come again to judge the living and the dead. All souls will be rejoined with their bodies, and those in Purgatory will be joined to the blessed in heaven.&quot;
From an individual's perspective, what is the difference between the first, immediate judgment (for those who have died before the 'end of time') and final judgment? Is it solely that the souls in purgatory are 'judged' ready for heaven?
This answer is based on a Catholic Answers website article by Catholic Apologist Tim Staples:  Why Are There Two Judgments.
From an individual's perspective, according to CCC 1022, upon death the immortal soul immediately enter into one of possible 3 states (as particular judgment):

the blessedness of heaven immediately [for the saints]
the blessedness of heaven through a purification [purgatory]
immediate and everlasting damnation

It is important to understand purgatory and hell properly, not principally locations, but states of being, since the soul is not yet joined to its body.

They are pure spirits. So we can’t really speak of hell being a “place” right now, at least, not as we understand “places.” However, after the resurrection, because those in hell will have bodies we could certainly speak of them having a “location” or “place” of sorts.

Hell is, as CCC 1033 says &quot;[the] state of definitive self-exclusion from communion with God and the blessed.&quot;  CCC 1472 says:

These two punishments (speaking of purgatory and hell) must not be conceived of as a kind of vengeance inflicted by God from without, but as following from the very nature of sin.

If the soul has been judged, what's the purpose for final judgment?  The article cites 3 reasons what the soul can expect at Final Judgment:


The final judgment will reveal in full the justice and glory of God for all to see. This is not accomplished in each man’s private and particular judgment.  (see CCC 1040)
The full implications of the good and evil that we do in our lifetime will not be fully realized at the time of our particular judgment
Since we sin and perform virtuous acts as a body/soul composite, it is fitting that we be judged as a body/soul composite as well. This too does not occur at our particular judgment, at the final judgment.