The direction of these oscillations is the difference between longitudinal or transverse waves. In longitudinal waves, the vibrations are parallel to the direction of wave travel. In tranverse waves, the vibrations are at right angles to the direction of wave travel.
Mechanical waves cause oscillations of particles in a solid, liquid or gas and must have a medium to travel through. Once the wave has passed, the medium ends up back in its rest position.
For example, after a wave reaches the beach, the sea ends up back where it started. Similarly, when a sound travels, there isn’t a wind that moves with it - the air ends up back where it started.
Mechanical waves can be longitudinal or transverse.
Electromagnetic waves cause oscillations in electrical and magnetic fields. All electromagnetic waves are transverse.
Waves are described using the following terms: