How are replicators and particle systems different?
Although the replicator and particle systems share many parameters, they’re very different tools. Both use layers (shapes, text, images, and so on) as cell sources and both generate onscreen elements from those sources. However, each produces a unique effect from those raw materials. A particle system generates dynamic (animated) elements that change over time: Particles are born, emerging from an onscreen “emitter”; they move across the Canvas; and they die, according to the “laws of nature” you specify in the parameters of the system.
A replicator, however, is not a dynamic simulation. Its elements are not emitted like particles, and thus have no birth rate, life, or speed parameters. The replicator builds a pattern of static copies of a source layer in an arrangement that you specify. Although the replicated elements you see onscreen are static by default, you can animate a replicator’s parameters. For example, you can designate a simple star shape as the source of your onscreen pattern and then replicate the star multiple times along the outline of a circle. By keyframing a few parameters of your new replicator object, you can launch the stars into animated orbit around the center of the circle, making them change color as they whirl.