After she figured out that you do know what datajacks are but are unsure how skilljacks work, she starts to explain.
I'll keep the color black to make it easier to read.
Also, yee be warned, this might be my interpretation of how it works when it comes to details. For Scarcrow, Mark and Cinder, this is reality, however 
"The main difference is that a datajack sends information to your commlink. You can have a link without a jack, but not the other way round. Skilljacks, however, send info to your wetware directly. So, if you slot a knowsoft for, say, French, neuromedicine and you see a cut-open brain, the skilljack basically hijacks the signal from your brain, interpretes it on his own, generates a very sophisticated response and sends it back to the other parts of the brain. Thus, an outsider won't figure out why you can tell the amygdala from the hypothalamus, and basically, so won't you. There is a difference, however: Skilljacks don't change your brain. In fact, they
preserve it from changing. Usually, when I explain you the difference between the amygdala and the hypothalamus, you learn. If you have a skilljack, however, you don't, because all the information is redirected to the jack.
That's why they never became as popular as people thought they would be when they entered the market. People dreamed of becoming neurosurgeons in a day, and famous footballers in another. But they didn't. Unless you spend a really, really, really big amount of money in good jacks, good softs and, of course, the skillwires to send all the relevant information to your muscles, you stay mediocre. You don't buy skilljacks and something you wanna be good at, because you will always be mediocre and have no chance to improve. And who spends a lot of money and pain in becoming mediocre in something that's not important for them?
Nobody. That's why they're hardly being used.
I hope you don't plan to acquire some, do you?"
