I have myself only heard of the 2 classes mentioned as one with heavenly hope and those with earthly hope, beyond that nothing about those on earth themselves been split up into classes, I know that there is a another 1000 years mentioned when satan gets released again to test those brought back to life on earth who never had a chance to know God.
here's an extract of how they describe it on there website no mention of 2 earthly classes that I can find.
Under the rule of Jesus Christ and his heavenly corulers, peace and happiness will prevail in all the earth. ( Psalm 37:9-11 ) Those in God's memory will be resurrected and will enjoy perfect health. ( Acts 24:15 ) By their faithfulness to God, obedient mankind will be granted what our original parents lost—everlasting life in human perfection on a paradise earth.— Revelation 21:3, 4 .
In the Bible book of Isaiah, we get a preview of what life will be like in the Paradise earth. No inhabitant of Paradise will say, "I am sick." ( Isaiah 33:24 ) Animals will pose no danger to man. ( Isaiah 11:6-9 ) People will build beautiful homes and inhabit them and will plant crops and eat to satisfaction. ( Isaiah 65:21-25 ) Moreover, God "will actually swallow up death forever, and the Sovereign Lord Jehovah will certainly wipe the tears from all faces."— Isaiah 25:8 .