The first may simply have valued money less than the other at the margin, which means, given the relative amounts of money and other goods that each commanded when making decisions. Most economists are so afraid of contaminating their analysis with value judgements that they will freely admit, even insist, that economic theory cannot decide whether one set of arrangements is better or more in the public interest than another. Many of these same economists fail to see, however, that the economic way of thinking also cannot determine whether one set of arrangements is more efficient than another. That may be an interesting and important claim, but it is not as significant as the claim that they are inefficient. And the latter claim has no foundation in economic theory.
Efficiency refers ultimately to valuations.
Because prices and values are not the same, the economic way of thinking cannot pronounce on the relative efficiency of alternative arrangements. It is often said that rush-hour urban traffic is inefficient because it is made up predominantly of single passenger vehicles. That is an insupportable claim. Those who drive alone rather than forming a car pool or taking the bus are implicitly showing that they place a higher value on the benefits relative to the costs of driving alone than of any available alternative. For people with the appropriate values, the most efficient way to commute to work could be in solemn procession, carrying candles and chanting psalms.