Vinegar is made by first fermenting sugar into alcohol with yeast and then a bacteria converts the alcohol into acetic acid.

White vinegar is distilled so it contains to a certain level of purity only acetic acid and water.

Apple cider vinegar uses apples as the source material and isn't distilled so it contains some apple flavor.

Apple cider vinegar is just white vinegar with a little flavor.

It's also a favorite of health wonks. It don't mean the opposite of everything the crazies say is true, but you get a lot of people with virtually no information "teaching" each other about apple cider vinegar which leads to the silly idea that apple cider vinegar is a base.

Apple cider vinegar is made through the same fermentation process as regular vinegar, just using apples to create cider and then further fermenting it to create vinegar (hence "apple cider" vinegar). All vinegar is made through the fermentation of ethanol (and that ethanol is fermented from a variety of sources depending on which type of vinegar you are buying). Furthermore, the Wikipedia page[1] clearly says

> Acetic acid and malic acid give [apple cider] vinegar its sour taste.

Not to mention that bases don't taste sour (they taste bitter or soapy), and given that you can use apple cider vinegar (as with any other vinegar) to add sourness to food I'm a little confused why you'd think two types of vinegar have fundamentally different chemistry.

[1]: https://en.wikipedia.org/wiki/Apple_cider_vinegar

Like lemon, apple cider vinegar is said to produce alkaline byproducts and lower your body pH after consumption, which might be true but doesn’t mean either is a base.