discuss the similarities and especially the distinctions between heat work and internal energy

Both heat and work have some similarities in the way they behave that you will have to consider. First both heat and work are directional quantities. This means that both of them have a certain magnitude and direction in relation to whether the energy is entering or leaving the system

Second, both heat and work are only recognized when energy crosses the systems boundaries. Third, building upon the second statement, systems only contain energy not work or heat. Fourth, both heat and work are associated with a process as the system follows a path from one state towards another state