In this paper, we propose different methods to quantify similarities of compositional texture in symbolically encoded piano music. A melodic contour or harmonic progression can be shaped into a wide variety of different rhythms, densities, or combinations of layers. Instead of describing these textural organizations only locally, using existing formalisms, we question how these parameters may evolve throughout a musical piece, and more specifically how much they change. Hence, we define six distance metrics to compare texture between two musical bars, based either on textural labels annotated with a dedicated syntax, or on raw musical content. We propose an evaluation methodology based on textural homogeneity and contrasts in classical Thema and Variations using the TAVERN dataset. Finally, we illustrate use cases of these tools to analyze long-term structure, and discuss the impact of these results on the understanding of musical texture.