Many people confuse pickling and fermenting because they both involve preserving vegetables and both are typically stored in jars. The easiest way to identify the difference is taste: pickled vegetables have a vinegar flavor and fermented vegetables are sour and tangy. What you can't see or taste is the phenomenal probiotic and health benefits that fermented vegetables have over pickled.
Pickling refers to anything that is preserved by acidity, typically vinegar. Although vinegar is healthy in moderation and is created through fermentation, pickled foods are boiled for preservation, killing all bacteria and many vitamins. The pickles you find on a store shelf in a jar have been pickled in vinegar and then boiled, as have all the other vegetables kept in heat-processed jars. If homemade, pickled vegetables don't have to be boiled, but typically are for the dry storage convenience. If not properly canned, pickled vegetables can also be subject to botulism risks, which has been on the rise in 2017; learn more about botulism here.
Fermented pickles, on the other hand, are found in refrigerator and are not in heat-processed jars (the lids don't have a concave, air-tight seal). These pickles have also been made in an aerobic environment, but with a simple salt-water brine. These types of lacto-fermented vegetables are full of healthy bacteria and probiotics that are not killed by any boiling sterilization. Although lacto-fermentation is a preservation method, the final product has to be stored in the fridge, making fermented vegetables less desirable for grocers to carry and much more expensive. Fermented vegetables often include sauerkraut, kimchi and pickles. But remember: if its not stored in the fridge, it's likely not fermented and definitely doesn't have any bacteria/probiotic benefit!
Start fermenting at home in Mason jars with the Complete Fermentation Kit. It has enough supplies for 4 ferments, plus a step-by-step recipe book so you never get lost.