Well, cutting a long story short, most of the melodic lines have had their synth settings redesigned for this mix. So the drawbar organ template from the BellMetalArp pak is now a cheesy electric organ and the EmPiano lead is tweaked for a more retro kind of sound. A string template from GenMix1 pak has some heavy EQ and pitch modulation in a bid to make it sound like a Mellotron in need of a service. And a halftime synth stab from the Arp pak has been revoiced completely into a kind of guitar/electric sitar lead thing.
All the revoicing was done via the Sounds button in the cell edit view in the mixer so if you look there you'll see the synth settings. Quite a lot of the voices are using the Dsynth tone generator module as an FM synth. This has only become possible with v3 because one of the new "under the hood" features is that the Dsynth will now track notes in the same way as the standard tone generator modules - meaning you can now apply an offset to the incoming note being tracked. That lets you stack several instances of the Dsynth in a fixed harmonic relationship.
So, with this new addition, a module that was previously useful for making mostly percussive drum sounds is now a very flexible source of all kinds of melodic sounds, combining elements of FM and additive synthesis.
The other big difference between this mix and those possible under previous versions is it uses per channel FX on some of the drum sounds. The drums are all from the latest versions of the Generative Drum paks which use some good quality drum samples prepared specially for these paks, rather than using the built-in General Midi synth.
Revoicing the Gen Drum pak in this way allowed each element of the drum kit in use to be allocated its own midi channel (rather than everything having to be on Channel 10 as it is when you use a General Midi synth).
If you open the cell FX tab on a drum voice in this mix while it is playing, you can see the activity for each midi channel in use. So, for example, the kick drum is on channel 1. This allows you to apply FX just to that channel without affecting the rest of the drum kit. So, in this mix, the kick drum has some very serious compression applied that acts to really pump the sound up but that does not affect the behaviour of the snare or hats, as it would if you put the compressor into the voice line FX slot in the mixer view.
You hear this at its most obvious in the middle section when there is a large reverb applied to just one tom drum (on channel 3) to make it really boom. If you applied reverb like that to the entire kit it would be unlistenable.
And, of course, all of these changes would be meaningless if it were not for the fact that you can now save them as part of the mix so they can be shared with any other mixtikl user.