How Ductile is Iron?

I've been doing research into materials used in plumbing as I'm on a course.

(No, I am not cheating merely asking some queries to understand materials better. The questions haven't been that in depth or at least not at the moment, but then it is a plumbing course not a mechanical engineering one)

I've been comparing ductility and malleability, at first I had trouble explaining the two then I discovered that ductility refers to tensile stress where as malleability refers to compressive stress.

I know iron doesn't like a lot of working but I've seen this list that puts it's ductility ahead of aluminium and copper, with gold the most ductile and lead the least; gold, silver, platinum, iron, nickel, copper, aluminium, zinc, tin, lead.

I've seen a tensile test where the iron was quite violent when it went and it flaked and fractured in a vice, so I would've thought it would be below lead.

I was told that iron with carbon is steel and at 3% malleability drops off but I've seen in textbooks iron with low amounts of carbon refered to as varying types of iron, no mention of steel anywhere.

I've seen malleable iron fittings to go with Low Carbon Steel tube, but if the tube has low amounts of carbon wouldn't it then be called iron tube, but then how do you get iron to be malleable.

I've completed and passed the section on materials and going onto the next phase Cold Water Systems.