Composite-to-composite describes the structure of the compared terms, while tamthīl describes the nature of the shared respect. They frequently overlap, but they are not simply two interchangeable definitions.
Battlefield dust with blades flashing above it, compared to night with stars, uses two integrated scenes and derives resemblance from their coordinated pattern. It therefore offers a clear illustration of representational resemblance.
A line may contain many words yet have a simple, individual shared feature. Verbal abundance cannot by itself establish tamthīl. Always distinguish the construction of the terms from the extraction of the common feature.