Quoted from
http://en.wikipedia.org/wiki/Obverse:
"Generally, if in doubt, the side of a coin with the larger scale image will be called the obverse (especially if the image is a single head) and, if that does not serve to distinguish them, the side that is more typical of a wide range of coins from that location will be called the obverse."
".... the obverse side of a modern piece of currency is the one that evokes that reaction by invoking the strength of the state, and that side almost always depicts a symbol of the state, whether it be the monarch or otherwise."
".... [the secondary side] typically is used to reflect the country's culture or government, evoking some treasured aspect of the state's territory, its philosophy of governing, or the culture of its people. In any case, this secondary side usually is less focused, and probably always less central, than the obverse, to the facilitation of the acceptance of the currency."
Given this, I think the the left side image of both coins depicted in the original post are the obverse, as they bear the name of the nation of origin and the value of the coin.