define electon affinity. is there any difference b/w electron affinity and electron gain enthalpy?

Electron gain enthalpy is the enthalpy change taking place when an isolated gaseous atom accepts an e- to form a monovalent gaseous anion.
X_(g) + e- -----------> X^-_(g)
This process of adding an e- can be either exothermic or endothermic which depends on the element.For ex- halogens have very high negative e- gain enthalpies while noble gases have large positive e- gain enthalpies.
Electron affinity is generally taken to be equal to the negative of the e- gain enthalpy.If energy is released when an e- is added to an isolated gaseous atom,the e- gain enthalpy is taken as positive.If energy has to be supplied when an e- is added then e- affinity is taken as negative.

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