Involuntary action is the set of muscle movement which do not require thinking. But it is controlled by brain for example beating of heart beat. While on the other hand, the reflex action is rapid and spontaneous action in response to any stimulus which doesn’t involve brain. For example – shutting eyes immediately when bright light is focused on them.

Involuntary Actions:
Involuntary actions are the actions that occur without conscious control or awareness. These actions are controlled by the autonomic nervous system and are essential for the body's survival. Here are some key points to understand involuntary actions:

1. Definition:
Involuntary actions are the actions that are not under our conscious control and occur automatically in response to certain stimuli.

2. Examples:
- Heartbeat: The contraction and relaxation of the heart muscles are involuntary actions that occur continuously without our conscious effort.
- Breathing: The inhalation and exhalation of air is another example of an involuntary action.
- Digestion: The movement of food through the digestive system and the secretion of digestive enzymes are also involuntary actions.
- Blinking: The reflex action of blinking to protect the eyes from foreign objects is an involuntary action.
- Sneezing: Sneezing in response to irritants in the nasal cavity is also an involuntary action.

Reflex Actions:
Reflex actions are a type of involuntary actions that occur in response to a specific stimulus. These actions are controlled by the spinal cord and do not involve conscious thought. Here are some key points to understand reflex actions:

1. Definition:
Reflex actions are rapid and automatic responses to a particular stimulus that do not require conscious thought or decision-making.

2. Characteristics:
- Quick response: Reflex actions occur rapidly, without any delay, to protect the body from potential harm.
- Involvement of spinal cord: Reflex actions bypass the brain and are controlled by the spinal cord, allowing for immediate response without the need for conscious processing.
- Consistency: Reflex actions are consistent and predictable. The same stimulus will elicit the same reflex action every time.

3. Examples:
- Knee-jerk reflex: When a doctor taps the knee with a reflex hammer, the leg automatically jerks forward.
- Withdrawal reflex: When touching a hot object, the hand automatically pulls away to avoid further injury.
- Pupillary reflex: The contraction or dilation of the pupils in response to changes in light intensity is a reflex action.

Key Differences:
- Involuntary actions encompass a broader range of actions that occur without conscious control, while reflex actions are a specific subset of involuntary actions that occur in response to a particular stimulus.
- Involuntary actions are controlled by the autonomic nervous system, while reflex actions are controlled by the spinal cord.
- Involuntary actions are essential for the body's survival and include activities such as heartbeat and digestion, while reflex actions are immediate responses to potential harm.
- Involuntary actions can occur continuously without external stimuli, while reflex actions require a specific stimulus to elicit a response.
- Involuntary actions can be influenced by conscious control to some extent, while reflex actions are purely automatic and bypass conscious thought.