What is the difference between a redshift and a cosmological redshift?

Redshift and cosmological redshift are both related to light and how it behaves as it travels through space. Simply put, redshift refers to the shift in the wavelength of light, which occurs when an object that emits light is moving away from the observer. This shift occurs because the wavelength of the light gets stretched out as the object moves away, causing it to appear more red (hence the name redshift).

Cosmological redshift, on the other hand, is a bit more complex. It is caused by the expansion of the universe itself, which causes the light emitted by distant galaxies to be stretched out as it travels through space. This means that the light arrives at Earth with a longer wavelength, which is what causes the redshift.

The key difference between redshift and cosmological redshift is the cause of the shift. Redshift is caused by the relative motion of an object emitting light, while cosmological redshift is caused by the expansion of the universe itself.