Meditation is a practice. Those who meditate deeply and within become 'non-local' and often leave their body's location. There are many ways to leave the body (more generally known as Out of Body Experience AKA 'OBE'). Mediators can 'leave' in a variety of OBE methods. Typically they are mental or spirit based versions of travel (no physical or energy body).

Astral travel is a specific form of OBE involving the projection of a duplicate energy (ethereal) and mental (awareness) body.

Though Astral travel is not the most common type of OBE during meditation, it does occur.

[advanced] The different forms of OBE have to do with what aspects are projected. Other than astral travel, phasing (a version of mental projection ref: Robert Monroe) is the most commonly practiced in the 'West'. Phasing is mostly a projection of a duplicate mental (awareness) body though certain energy abilities can also be projected. Note that there is no duplicate energy body. Many other combinations of bodies and aspects can be projected using a wide variety of OBE methods.