It is a few selected PCM's from different SRX + AX Synth + some new ones i think.
It also includes the drumkits from Roland JD-Xi.
Zenology Pro has 1840 PCM which is almost 50% more than the XV 5080 but when i looked closer i noticed that some of them are the same in various pcm banks so it is closer to 3-400 more in total.
The Zenology Pro also have more filter variations to choose from + the new ones are 12-18-24 Pole and the other are 12-24 Pole while the XV 5080 is 12 Pole only or you can hack it to use both filters to get 24 Pole.
On the + side the XV 5080 has Reverb + more effects you can add to your patch at the same time vs Zenology Pro that only have 1 effect slot and no Reverb.