Horticultural vinegar is very different from the regular vinegar. Cooking vinegar contains no more than 5% acetic acid which makes it harmless to weeds and tough grasses for the most part. Horticultural vinegar contains more acetic acid which allows it to penetrate into the root system and kill them. Horticultural vinegar will damage some grasses and flowers. So good to avoid collateral damage or vinegar flowing downhill after being applied.
Edited to add that it also changes soil pH for a time until rain or watering or other forces of nature dilute it.
