Difference Between Steady State and Equilibrium

"Steady State" and "Equilibrium" are two situations where the properties of the system do not change with time. Since both these conditions tell us that there is no change in the properties of the system with time but still both are different from each other. First we will understand about steady state and equilibrium state one by one and then later we will differentiate between the two how steady state differs from equilibrium state. 

Steady State
"A system will be in a steady state condition with its surroundings when the properties of the system do not vary over time at a specified location within the system whereas these properties may vary from one location to another within the system". 
In a mathematical form, say temperature, pressure, volume are the properties of the system. When the system is in the steady state condition then these system's properties at a specified location doesn't vary with time, Or we can say that, at a specified location;
➛ "The human body is a well-known example for understanding steady state conditions". 
Because you must have felt that the surrounding temperature is higher than our body temperature. And body temperature remains in steady state, as it does not change over time. Also our body temperature does not remain the same throughout. Sometimes, the upper body temperature is higher than the lower body temperature.
➛ System's property changes from one location to other within the system when the system is in the steady state condition.
As shown above, the properties of the system at a specified location (Say, location-1) within the system do not change over time, whereas these properties vary from one location to another within the system (Say, location-1 and location-2).

Equilibrium
"A system will be in a state of equilibrium (or in equilibrium condition) with its surroundings when all the properties of the system remains the same throughout within the system and do not vary with time (or have the same properties of the system and surrounding)". 
In a mathematical form, say temperature, pressure, volume are the properties of the system. When the system is in the state of equilibrium then these system's properties don't vary with time Or we can say that throughout the system;
             ஃ ∆T ＝ ∆P ＝ ∆V ＝ 0
For Example- 
The temperature difference between the system and the surroundings is an example of a state of equilibrium because heat transfer between the system and the surrounding (or two systems) occurs when the driving force is the temperature difference and this heat transfer will continue until the temperature of the system and surrounding becomes the same (∆T= 0). 
Let us understand this with a figure;
➛ "Therefore, the property of the system remains the same at any location within the system when the system is in a state of equilibrium".
➛ In the state of equilibrium, no driving force is present so the properties of the system no longer change.  
➛ In thermodynamics, we study "thermodynamic equilibrium". And its statement is as follows- "A system will be in thermodynamic equilibrium with its surroundings when that system and its surroundings are simultaneously in thermal, mechanical and chemical equilibrium".
➛ 
As shown above, that at any location within the system (Say: location-1,location -2 and location-3) the properties of the system do not change with time after attaining the state of equilibrium. And it remains the same throughout the system.  

Difference Between Steady State And Equilibrium-
  1. Equilibrium refers to a closed system without net heat transfer while steady state refers to an open system with net heat transfer but no change in the state of the system.
  2. When the system is in a state of equilibrium with its surroundings then there is no net driving force between them, but when the system is in a steady state with its surroundings then there is a net driving force between them.
  3. For Example- Human dead body is an example of a state of equilibrium because in this state, there is no difference in temperature between the system (human dead body) and the surroundings and hence no driving force. Due to this, there is no heat transfer between the human dead body and the surrounding. Whereas sleeping human body is an example of steady state because in this situation, there is a difference in temperature between the system (sleeping human body) and its surroundings and hence, the driving force exists here in the form of temperature difference. Due to this, the transfer of heat continues between system (sleeping human body) and the surrounding but the temperature of the human body does not change with time.
In Steady State Condition
While In Equilibrium Condition;


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