An astringent is usually stronger than toner & is alcohol & chemical based. This gives it anti-bacterial properties. Usually recommended for acne prone skin or extremely oily skin. Astringents destroy bacteria, help control oil, acne breakouts, pimples, & blackheads. Astringent use on a lesion due to acne or a pimple may cause a stinging sensation, which is pretty normal.
Toners are usually mild & used for hydrating sensitive, extremely dry skin & aging skin as well. It also helps your keep your pores clear. It cleans the skin & you will not find your skin feeling dry after the use of a toner. Its great for combination skin, as it helps in clearing the clogged pores due to the oils, and hydrates the dry areas of the skin.
Oily & acne prone skin should use an astringent.
Dry & sensitive skin should use toner.
Remember to always use your toner or astringent after cleansing & before applying your moisturizer.