All very similar. I think it also depends on your taste. Something is Sour or Tart because it usually contains a kind of ACID, therefore is ACIDIC. Tart and Sour are different degrees of acidity/bitterness. Tart is usually less acidic, sweet with a touch of sour (still delicious). Like some grapes, kiwi fruit or berries. But sour can be too sour and not edible like a lemon or 醋. -KK

Sour is a taste, acidic is one, which creates acid and acid is a dangerous substance or drug)))