The Mishna says:
Be quick in performing a minor commandment as a major one. [Avot 4:2]
But we do not rank the commandments. The Mishna also says:
Be as scrupulous in observing a minor commandment as a major commandment, because you don't know the values of the commandments." [Avot 2:1]
All this is consistent with saying: "Mitzvot may well differ in value, but since we don't know what these values are, we must treat them as equal."
But then, the Talmud says that a candidate for conversion is "given instruction in some of the minor [commandments] and some of the major commandments". [Yevamot 47] These words even appear on the conversion certificate. How does the converting rabbi decide what's major and what's minor?
Instead of leaving it to the converting rabbi to decide what mitzvot to teach, couldn't the Talmud have specified them, without characterizing them as major or minor?