all purpose flour or cornstarch..... whats the difference?

Both can be used as a thickener such as for sauces and gravies. Cornstartch however makes a sauce smoother. I use flour for baking. I haven't personally heard of cornstarch for baking though.

The previous answers are both correct - cornstarch (or cornflour as it's called in the UK) is generally used for thickening gravies and sauces, flour can also be used in the making of sauces (roux-based in particular, like bechamel). But unlike the previous two respondants, I have encountered a baking recipe which uses cornstarch as an ingredient: strawberry shortcake. It uses wheat flour too (all-purpose), but also requires cornstarch. The end result is a kind of sweet, crumbly thinn-ish spongey "shortcake", which is layered with strawberries and cream. This recipe shouldn't be confused with shortcake biscuits (cookies) or shortbread. It's more of a cake/cookie gateau/dessert-type thing, and is very tasty. However, unless the recipe specifically states that cornstarch should be used, I wouldn't advise it, as the results will be very different to the intended ones. The difference between cornstarch and flour is similar to the differences between powdered sugar and granulated sugar. They both behave very differently, and need to be treated differently. I hope this helps!!

cornstarch is very different... it's meant for gravy and the like. i don't think it'll work if you used it as a replacement. all purpose flour can be used to make gravies in place of corn starch but not the other way around.

flour is made from wheat cornstarch from corn. flour makes bread but you cannot use cornstarch for making bread.cornstarch is used merely to thicken foods and puddings and not for making bread. they are two completely different products entirely.