Pickled vegetables using vinegar brine contain vinegar as a main acid. It is somewhat sharper than the mixture of different acids produced by the fermentation method. Here you have vinegar, lactic acid and other chemical byproducts of happy life of your culture including a little amount of alcohol (though this process is done with air access, unlike making alcohol, where there must be no oxygen present, or your alcohol making turns into vinegar production).
1. vinegar brine method:
Vinegar is the main acid. The taste is sharper and differs depending on the recipe and amount of salt, sugar water and spices. It is the more stable way to preserve and gives more reliable results with little expertise. Results vary mainly season to season from the vegetables' quality (flavours and texture) You can use different types of vinegars from different processes (apple cider vinegar, wine vinegar) and shift the flavour of your results. It's a very tasty way of preserving vegetables. There is some loss of vitamins due to heating, but your product lasts longer.
2. fermentation method:
The process requires better knowledge of precautions, methods, and combination of ingredients. The flavour is more fruity due to the combination of more different acids and a little alcohol and other products of the culture. It's less sharp, and also depends on the length of process, temperatures, and qualities of the ingredients. So generally this process is more "colorful" in result and more unpredictable. To get reliable results you have to master the process. Imagine it like master wine makers. This method preserves vitamins, but products are best kept in the fridge or cellar and the shelf life is shorter and depends on for how long your mix will stay alive. Otherwise you would have to sterilize it in later stages and destroy vitamins.
In summary: Flavour is different, because different chemicals are present. Vinegar pickles have vinegar; fermented pickles have vinegar and other flavours.