yeah you're right. toners and astringents are essentially the same type of product. but the difference is that toners are for normal to combination skin with an alcohol content of 4 to 15%, they also tone, (or tighten )the skin.
in an astringent they can have alcohol up to 35% and are for oily and acne prone skin.they help to remove excess oil but can be too drying and cause more harm than good. when i was in school my teacher told us that if you use an astringent and you look at your cotton or whatever you're using it looks like dirt, but what it actually is, is your acid mantle which is used to protect your skin from bacteria and microorganisms. the acid mantle may also help in the skins shedding and renewal process. well man that was a lot of typing, hope it helped.