AIR The Keys Collection

I rate AIR products typically very highly. However, I'm quite confused: how are they related to their earlier line of products? Is it brand new software, enhancement of the old software, or simply a new name and interface? The descriptions don't make it any clearer. For instance, once I purchased a VST called "Drum Synth 500". Is the current "Drum Synth" related to this? If no, I really admire the creativity in name coining;).