Bringing the four elements together clarifies how the subject, model, particle and ground work together. The first two examples state their ground; the last relies on context.
ExpressionSubjectModelParticle / ground
العلم كالنور في الهدايةKnowledgeLightkāf / guidance
الورق كالحرير في النعومةPaperSilkkāf / softness
جعلنا الليل لباسًاNightCoveringomitted / concealment
The table is more than an exercise in naming parts: it helps preserve the intended limits and exact purpose of each comparison.