I think the former one is usually used to describe an individual building and the later one is to describe a specific living place like 'a set of apartment'

Actually, in China we usually use yi dong fangzi to describe a building which have many floors and yi tao fangzi means a single house or an apartment. For example, in downtown, we always say someone buy yi taofangzi（一套房子）not yi dong fangzi（一栋房子）

Yi doing fang zi : a building Yi Tao fang zi : a house Italki mandarin tutor:张琪 Jo