So Pickling + Fermentation, Same Thing–Right?
Wrong, the quick and dirty of pickling vs fermentation is that pickling involves heat processing and fermentation does not.
When you pickle, you usually heat vinegar, salt, and sugar (which is called "brine") in water and pour it over the vegetables. To make the pickles shelf-stable, you can them using a canner (a big pot that you put the jars in to get them to seal).
When you ferment vegetables (there are so many other ferments and methods!) you generally use a salt water brine and submerge your chopped (or not) vegetables underneath the brine using a weight of some sort. The brine creates an environment that is conducive to the growth of "good bacteria" (lactobacillus plantarum in this case) and prevents molds and such from growing on the vegetables (which would happen if they were exposed to air). Fermentation also involves time– sometimes a lot, sometimes a little, depending on your desired result. Some sauerkrauts can ferment for months. Ideally, you'd ferment for more than 5 days to hit a good flavor and probiotic level. You can check the pH to make sure if you don't trust your tastebuds, which should read lower than 4.0. Ferments are not usually canned after they are done fermenting because the heat would kill the good bacteria. Instead, they are stored in a cool environment to slow down the fermentation (in the case of refrigeration, it nearly stalls the process).