* Mechanical waves require a medium: Mechanical waves need a physical medium (like air, water, or a solid) to travel through. They are caused by vibrations within this medium.

* Light is an electromagnetic wave: Light, on the other hand, is an electromagnetic wave. It doesn't need a medium to travel and can even travel through the vacuum of space.

How light travels:

Light travels as oscillations of electric and magnetic fields. These oscillations are perpendicular to each other and to the direction of the wave's travel.

Key differences:

* Medium: Mechanical waves need a medium, electromagnetic waves don't.

* Nature: Mechanical waves are caused by vibrations in a medium, electromagnetic waves are caused by oscillations of electric and magnetic fields.

* Speed: Mechanical waves travel at different speeds depending on the medium, while the speed of light in a vacuum is constant.

Examples of mechanical waves:

* Sound waves

* Water waves

* Seismic waves

Examples of electromagnetic waves:

* Light (visible, infrared, ultraviolet)

* Radio waves

* Microwaves

* X-rays

* Gamma rays