Which term refers to the difference between objects when they are placed next to each other?

The term that accurately refers to the difference between objects when they are placed next to each other is contrast. In design, including floral arrangements, contrast is a fundamental principle that highlights the differences between various elements, such as color, shape, or texture. By showcasing these differences, contrast not only creates visual interest but also helps in drawing attention to specific components within a composition.

For instance, using bright colors next to pastel hues or pairing smooth petals with rough textures exemplifies contrast and can elevate a design's overall impact. This principle is essential in floral design as it guides the arrangement to be more dynamic and engaging for the viewer.

In the context of floral arrangements, other terms like variation may imply differences as well, but they do not specifically encapsulate the interactive relationship created when contrasting elements are placed together. Similarly, emphasis refers to drawing attention to a specific part of the design, while harmony indicates a pleasing arrangement of elements rather than their differences. Therefore, contrast is the most fitting term for describing how differences between objects are perceived when they are adjacent to one another.