If you need to compare, then If you have a sensitive ears, try listening this songs, and compare the VBR version and CBR version, you can hear the difference :
Spoiler:
Ayumi Hamasaki - Free & Easy
Ayumi Hamasaki - Don't look back
L'Arc~en~Ciel - STAY AWAY
Kalafina - Hikari no Senritsu
Do As Infinity - Rakuen
The Beatles - Come Together
The Beatles - Love Me Do
Utada Hikaru - Dareka no Negai ga Kanau Koro
Utada Hikaru - First Love
Vanessa Mae - Toccata & Fugue In D Minor
Bond - Shine
Actually it's so many, but those list is enough I think.
Well, not only the list, but most of the songs, I believe.
What's really obvious with those songs that can perform better in VBR than CBR?