Entropy is property where as enthalpy is energy.
Entropy is function of quantity of heat, the property of the system which decides the percentage of heat that can be converted into work. Entropy shows the randomness of molecules.
For example, if your are giving 100J of heat to a system to convert that heat into work, you cannot get 100J of work practically, the system is having some property “entropy” which resists the conversion of heat, so you can only get less than 100J of work.
What is entropy ?
Whatever the medium either solid or fluid, it consist of molecules, the measure of randomness of molecules is called as entropy, hence if the randomness of molecules is more, then the increase in entropy in a process will be more, hence the percentage of heat that can be converted into work will be less. In other words, entropy is a function of quantity of heat.
If the randomness of molecules is less, then increase in entropy will be less, so work output will be more. That’s why entropy of solid is less than entropy of gases since gases are having more random molecules than solid. Entropy of system and its surroundings combined always increases i.e entropy of universe always increases.
What is enthalpy?
As we said above enthalpy is energy, the sum of internal energy and flow energy is called as enthalpy.