The important idea here is how far you stop the material from moving. Containment is about holding the hazmat in place within the immediate environment—keeping it from spreading to other parts of the same room, building, or site. Confinement is about preventing the release from crossing the defined boundary you’ve set for the incident—keeping the hazard from leaving the perimeter and reaching exposed areas outside. For example, using barriers, absorbents, and secondary containment inside a spill area helps prevent the material from migrating within that space. Establishing a perimeter, sealing doors, and creating physical barriers around the incident work to keep the release from moving beyond the defined boundary. Other descriptions that mix the idea with packaging size, heat, or administrative controls don’t match how hazmat control differentiates these concepts. The clearer distinction is about how far the material is allowed to go: contain within the environment, or confine within the boundary so it doesn’t escape the defined area.