it's the same word, Fabian. Most people who use this word think it is short for wee'uns (wee ones, small ones) but I think it is probably an expression that has been around a long time and actually comes from the word "wean". It is used in Scotland as well. In northern (northeastern esp) Scotland a different word is used, "bairn", which is of Scandinavian origin.

People don't say "diapers" in Ireland or in Britain ; it's "nappies"! And weans, wains, wee' uns is used for toddlers and even school age children.