what is the difference between ionisation energy and electrogain enthalpy?

Ionization energy is the amount of energy required to remove the valence electron from an isolated gaseous atom. On the other hand,electron gain enthalpy is the amount of energy released when an extra electron is added to the valence shell of an isolated gaesous atom.

Ionization Enthalpy is the energy required to remove an electron from an isolated gaseous atom in its ground state. it is also known as ionization potential. The ionization enthalpies required to remove first,second,third, etc electrons from an isolated gaseous atom are successive ionization enthalpies. Ionization Enthalpy is always positive. Ionization enthalpy is the minimum amount of energy which is required to knock out the most loosely bound electron from an isolated gaseous atom so as to convert it into a gaseous cation. whereas ionization energy is the amount of energy required to remove the electron from ground state to the infinity.

and. electron gain enthalpy is the change in enthalpy that takes place when an extra electron is added to an isolated atom in the gaseous phase to form a gaseous negative ion. it is also known as electron affinity. higher the electron gain enthalpy more is the energy released and stabler will be the negative ion produced.