Transverse and longitudinal waves are the two types of mechanical waves. Transverse waves involve the oscillation of particles perpendicular to the direction of wave propagation. An example of a transverse wave is a wave on a string or a water wave. In a transverse wave, the particles move up and down or side to side, perpendicular to the direction the wave is traveling.

Longitudinal waves involve the oscillation of particles parallel to the direction of wave propagation. An example of a longitudinal wave is a sound wave. In a longitudinal wave, the particles move back and forth in the same direction as the wave is traveling, causing compression and expansion of the medium.

Therefore, it is not correct to say transverse and congressional waves are the two types of mechanical waves. The correct types are transverse and longitudinal waves.