Bajo vs. reducido

The Spanish words 'bajo' and 'reducido' can both be translated to mean 'low' in English, but they are used in different contexts.

Bajo

'Bajo' is commonly used to describe something that is physically low, or to reflect levels such as prices, volume, or altitude.
El precio de la gasolina está muy bajo.
(The price of gasoline is very low.)
El edificio es muy bajo.
(The building is very low.)
El volumen de la música está bajo.
(The volume of the music is low.)
El avión está volando a una altitud baja.
(The airplane is flying at a low altitude.)

Reducido

'Reducido' emphasizes the idea of reduction or decrease and is often used when something has been lowered in quantity, size, or capacity as a result of some action or process.
Tenemos un presupuesto reducido este año.
(We have a reduced budget this year.)
El grupo de estudiantes es reducido.
(The group of students is small.)
Entendemos las limitaciones del proyecto debido al presupuesto reducido.
(We understand the project's limitations due to the reduced budget.)
La porción de comida es reducida.
(The food portion is small.)

Summary

Both 'bajo' and 'reducido' can mean 'low', but 'bajo' refers to something physically low or at a lower level, while 'reducido' implies that something has decreased from an original amount.