Similarities

i) Work transfer and heat transfer are transient phenomena. Systems do not possess heat or work. Whenever systems undergo changes of state, they can cross the system boundary.

ii) They are observed only at the boundaries of the system.

iii) They are path functions and inexact differentials.

iv) They are not a property of a system.

Differences:

i) Work transfer is defined as the way by which a system may exchange energy with its surroundings. Work is said to be transferred if a certain system is displaced by a force in the direction of it.

Heat transfer is defined as the form of energy that is transferred across the boundary of a system at a given temperature to another system or the surrounding at a lower temperature by virtue of the temperature difference between the two systems.

ii) In thermodynamics, the work done by the system is considered as positive work transfer and work done on the system is considered as negative work transfer whereas heat transferred to a system is considered as positive heat transfer and heat transfer from a system is considered as negative heat transfer.