Explain the differences between mass and weight among energy, heat, and enthalpy.

If you are thinking of the thermodynamic definitions Internal energy change is defined as the heat gained by a system less the work done by the system

E = Q-W. This combination is a state function meaning it depends on the initial and final states of a system and is path independent while work and heat change are path dependent.

Enthalpy change is defined as H = E+ PV A change in Enthalpy is also a state function. The most useful factor of enthalpy is that at constant pressure The heat of reaction Q is a measure of enthalpy and is also a state function.

hope this helps !!

gravity causes stares to cluster i think so