No. I do not want to compare both. I just want to mention that I am not around in SL at the moment because I play Minecraft with my brother currently.
Minecraft is completely differend then Second Life. SL gives me more freedom when I create things and I defenetly will be back soon! But hey! I must admit Minecarft is a lot of fun too,so I will spend some time there as we had some fun and laughing last days. :) We did build a castle out of these Minecraft blocks, so that we are save when it becomes night. Nighttime can be dangerous in Minecraft! There are spawning monsters which will hunt you.
But as I said.. I will be back to SL soon :)