hello. even japanese don't know the difference clearly (－－〆)… 家(いえ)is preferable to describe a building 家(うち)is preferable to describe your family and your household it is often said ''(いえ)means house .(うち)means home'' in addition ,(うち) is used as family,company,which you belongs to. for example ・・・うちは今景気が良くてな～　my company is doing well now. and japanese girls' うち　means ' I ', うちの means ' my ' sorry my pour English... this site explains the difference! http://dimitri2012.wordpress.com/2012/06/18/%E5%AE%B6%EF%BC%88%E3%81%84%E3%81%88%EF%BC%89-%E3%81%A8-%E5%AE%B6%EF%BC%88%E3%81%86%E3%81%A1%EF%BC%89-%E3%81%AE%E9%81%95%E3%81%84-the-difference-between-%E3%81%84%E3%81%88%E3%80%80and-%E3%81%86/

i think difference is just a way to speaking. What kind of situation, you can use いえ.

i guess it's like うち is used to pertaining to your own house .. like 私の家　→　○　私のうち and 家の中　→　○　うちの中 .. and 家is often used to call other people's houses. たとえば、その家 はきれいですね。 that's what i can comprehend for now from http://okwave.jp/qa/q1851312.html .. :)