It depends on a wide variety of factors, not necessarily the difficulty of the repertoire, but also how all the different aspects of the musical craft that aren't just about quick fingers are handled. It also depends on the taste of the jury, and sometimes, unfortunately, whose teacher is and isn't on the jury.
But as an example, who should get more points?
1) The person who plays an extremely hard Etude, but who does so in a mechanical fashion, with no variation in dynamics, no musical feeling
2) The person who plays a simple Chopin Mazurka, but with amazing sensitivity and feeling, with finely shaded dynamics, leaving everyone in the hall deeply touched
(Of course, in a competition everyone will likely have to play some difficult Etudes as well as simpler pieces but the point still stands)