How do you tell the difference between chestnuts and conkers?

I want to go and pick some chestnuts to make a mushroom and chestnut soup, but don't know the difference. I know they are both a kind of chestnut, but if I pick conkers by mistake and try to make soup with them, I don't think it would go down too well!

How do you tell the difference between chestnuts and conkers?
Conkers have a piece of string through them
Reply:I thought conkers were chestnuts.
Reply:The easiest way to remember chestnuts (conkers)is that they tend to be round,sweet chestnuts the ones you can eat have a flat side to them.When in doubt go to your green grocers and buy them there.safest way if your not sure.
Reply:conkers are rounder. chestnuts are pointed on one end. you'd be better buying some, they're cheap enough. you don't want to poison people.
Reply:Conkers grow on the Horse Chestnut Tree and Chestnuts grow on Sweet Chestnut Tree.
Reply:their casings are different. Conkers green casing is usually harder and the spikes are more firm that a chestnuts. I think that actual conkers are more round than chestnuts too.
Reply:Conkers are rounder than chestnuts. Chestnuts are a little more tear shaped and go into a point.

In there cases, conkers have hard spikes. Chestnuts have soft spikes.