Reflex actions are sudden actions performed in response to something in the environment. Examples include pulling our hand back from a flame or jumping out of the way of a bus. In reflex actions, we do something without thinking about it. Reflex arcs have evolved because the thinking process of the brain is not fast enough, making them efficient for quick responses to stimuli.

Involuntary actions are muscle movements over which we do not have any thinking control. Examples include heart beating, breathing, digesting food, blood pressure, salivation and vomiting. These actions are controlled by the mid-brain and hind-brain, specifically by the medulla. We cannot control these actions easily even if we wanted to.

The key difference is that reflex actions are sudden responses to environmental changes, while involuntary actions are ongoing processes that occur continuously without our conscious control.