I could be wrong but I think they are the same cables. The V2.1 has one advantage: the impedance is adjustable, where the V2's impedance is not. You should just call MIT to make sure.
I'm guessing you're asking about speaker cables*, so the question of adjustable impedance-matching does not come up.
Oracle V2 was an excellent speaker cable, but V2.1 is more open, has a more articulate bottom end with better pitch definition, and has better over-all soundstaging and holography.
* MIT never made an interconnect called "Oracle V2." The model prior to Oracle V2.1 interconnect was called 350 Oracle.
Hope this helps. Best, Joe
Thanks all and I am asking about speaker cables as Joe guessed. My friend has V2 and actually did an a-b test between V2 and V2.1 which belongs to another friend. He suggested that the V2.1's network boxes are smaller and lighter, and the sound is not as good as his own V2. I am interested in getting a pair for my Firebirds and I wonder if I get the V2, which is cheaper, I would be disappointed.