It's been so long since my Avalanche that a true comparison may not be accurate. However, I believe that the Rhino is a step above regarding performance.
My Rhino (Rico layout) was too shiny for the conditions I face, but after knocking the gloss off it came to life considerably. I can easily use it as the first, and only, ball at one of the houses I bowl with a stronger than expected reaction.
Without digging up the numbers on the Avalanche, my guess is that the Rhino has a higher differential. Surface-wise I just try to match up with what gives me the most forgiveness and carry.