How might one measure differences in living standards between less developed and developed countries? 

This is a very wide question where any clear and relevant calculate should merit marks. Explanation of standard of living as a wide range of issues - which must then be made measurable! For example, health care is hardly a distinct and measurable variable, but doctors per 1,000 citizens are. The way to address this question is therefore to not only exemplify with variables which are part of living standards, but also render them measurable in some way