Render Mode is a technical term that is extremely important in rendering and optimizing game graphics (technical art). In particle systems, settings that specify how particles are drawn on the screen as billboard, mesh, or horizontal/vertical board.
Real-world analogy: How to use "signboards" and "real props" used on the stage of a play
Render Mode is the ``actor's positioning rules'' that determine how the background and effects are displayed on stage. "Billboard" is a black character that rotates the direction of the signboard in real time so that it always faces the audience (camera). "Mesh" is the placement of a three-dimensional real sculpture (3D model) that can be viewed from any angle. "Stretched Billboard" is equivalent to having an afterimage signboard stretched in the direction of travel, like a bullet train running.
Figure: Infographic that clearly illustrates the basic processing flow and mechanism of Render Mode in Japanese notation
Detailed mechanism and operating principle
Change the Render Mode of the particle Renderer module appropriately (Billboard for smoke, Stretched Billboard for lasers, Mesh for 3D models, etc.).