No, a substation and a transformer substation are not the same thing, although they are closely related.
A substation is a part of an electrical generation, transmission, and distribution system where voltage is transformed from high to low or vice versa using transformers. Substations also serve as a control and switching point for electrical circuits. The main components of a substation include transformers, circuit breakers, switches, and protection and control equipment.
A transformer substation, also known as a transformer station, is a specific type of substation whose primary purpose is to transform voltage levels using power transformers. It steps up the voltage for long-distance transmission or steps down the voltage for distribution to end-users.
While all transformer substations are substations, not all substations are transformer substations. Some substations may serve other purposes, such as switching substations, which are used to switch and route power without transforming the voltage level.