What is the difference between aerobic and strength training exercise?

Aerobic exercise stresses the cardiorespiratory (heart and lungs) system, whereas strength training places emphasis on the musculoskeletal (muscles, bones, joints) system. Each should be performed as part of a comprehensive fitness program.

It is simple to think of this in terms of where each benefit. 

Aerobic training helps benefit the HEART. The heart is the most important muscle of the body and aerobic training helps lower cholesterol, improve stroke volume, lower blood pressure, lower resting heart rate, and burns calories.

Strength training benefits both the MUSCLES and the JOINTS. Strength training increases bone density, lean muscle mass ( resulting in higher metabolic rates throughout the day) and increases flexibility when done properly in balancing opposing muscle groups.

But both are needed to complete your fitness regimen. 

Strength training and aerobic exercise are both an important part of a balanced fitness plan. Strength training works on the over load principle, where you are lifting a heavy weight and are putting stress on the muscles. A chest press or a leg press machine are examples of strength training exercises. Aerobic exercise focuses on increasing the heart rate, often you hear about getting into a "target heart rate zone". Activities such as running, biking, or stair climbing are examples of aerobic types of exercise.

The difference between aerobic exercise and strength exercise is that aerobic means "with oxygen." Strength training typically falls under anaerobic forms of exercise which means "without oxygen." "Without oxygen" does not mean you are not breathing, it just means the type of energy your body is using.

Some forms of aerobic exercise is: walking, jogging, running, swimming, rowing, etc.

Strength training examples are: weightlifting, resistance bands, pull-ups, resistance training using one's own body weight as in a squat or push-up.

AEROBIC EXERCISE VERSUS STRENGTH TRAINING FOR WEIGHT LOSS

AEROBIC EXERCISE GENERALLY

• Burns more calories per hour than weight training.
• Builds little muscle.
• Has minimal effects on metabolism in the hours after exercise.
• Has greater effects on metabolism when workout is very hard.
• Can be done every day
• Needs to be done at least three times per week for sustained benefits.

WEIGHT TRAINING

• Raises resting basal metabolic rate (BMR).
• Raises the metabolism for several hours after the workout.
• Should be limited to three or four times per week.
• Produces benefits from as little as one hard workout per week.