These words are often used interchangeably albeit incorrectly. The ingredients in each product have very different uses. While there are many types of toners their basic use is similar.
Toners are used after cleansing the skin to remove any leftover dirt, oil or dead skin that wasn’t removed by your facial cleanser. They also prep the skin for application of your other skin care products. Skin absorbs active ingredients better when it is wet. Applying serums and moisturizers after toner helps drive the products deeper.
Using a toner for a specific need is beneficial for treating certain skin issues. Most toners are formulated to replenish the skin. For example, if you have dry skin then a toner formulated with hyaluronic acid or glycerin can help by boosting the amount of moisture. On the other hand, if you have acne-prone skin you may want to use a toner with salicylic acid to help remove excess oil.
Astringents on the other hand are alcohol based products designed to remove oil and do not nourish the skin. While some people may need and even benefit from an astringent they should be used only when completely necessary and sparingly. The harsh ingredients disrupt the acid mantle of your skin which throws off your pH balance leading to dry, red and irritated skin.
Bottom line, toners will work for almost anyone and there is a formula out there for any skin type and skin care need!