In this well known Mozart Piano concerto, there is two phrases between measures 41-56. By this time in the piece, the movement has already modulated to C major, the dominant of the original key. The two eight bar phrases are totally different from each other, sharing only an identical harmonic progression with the exception of the two cadence measures. The first phrase ends with a half cadence and the second on a imperfect authentic cadence. There is no modulation between the phrases, no links, no elisions, and no symmetry.
There are quite a bit of structural phenomena to talk about in the 1st movement of Mozart's K332. The composer puts only a few chromatics and suspensions in this exceprt, hinting at more non-chord tones to come. There is a crescendo from the first phrase piano into forte at the beginning of the seocond phrase that accompanies a register change. Most dramatically, Mozart arpeggiates the left hand in triple, while the right hand remains in two at the beginning of the last half. It provides a striking rhythmic contrast that is not found anywhere else in this piece. Immediately after, to better frame those first two measures of the second phrase, a drop in dynamics to piano occurs. This again leads to a forte at the end of the phrase and the conclusion of this excerpt.