Absolutely nothing. White vinegar is the choice vinegar for pickling due to it's acidic nature as opposed to balsamic vinegar, white wine vinegar, apple cider vinegar or red wine vinegar, etc. Just make sure that the white vinegar you do use is at least 5% acidity, that is normally what is available. Some people pre mix their vinegar with the pickling spices ahead of time and that's probably where the name "pickling vinegar" came from. It would be ready for when they needed it next time. There are plenty of recipes online that you can research for "pickling vinegar" but in essence, it's just a pre mixed vinegar with spices.