The difference is that JL doesn't start too many threads about his predictions, nor does he really go into sales comparisons. He'll make his prediction, post a thread about it, and then disappear until the next one.
And last time I checked, he was pretty close with his 20 million by the end of 2007 prediction. His more recent ones (4.1 million/month and 60 million end of 2008) are a bit more far fetched. But he doesn't really bother to try and get anyone to believe him or anything. Avinash never made threads about his predictions as far as I know.
Crazzy on the other hand makes many threads about a whole bunch of stuff, and in the thread he usually manages to destroy his own comparison through bad typing skills (or bad English), poorly thought-out argument, and usually all around just plain being wrong.
Then when you don't agree with him or try to disprove him, he either goes into a mis-quoting phase where he'll quote one sentence of yours that doesn't sum your argument at all, and then you'll have to repeat yourself to no avail. Then, he'll start getting angry (which can be measured by how many chins his smilies have), and then say something like "if you DON't believe in SONY DIMINATION leave THIS thREad."
The thread, however, will last another 10 pages with every other page being exactly alike, since every argument runs in circles when Crazzy is involved.