energy of activation vs activation energy

energy of activation and activation energy both are nouns.

Word	Noun	Adjective	Verb	Adverb
energy of activation	Yes	No	No	No
activation energy	Yes	No	No	No

As nouns, energy of activation and activation energy are synonyms defined as:

energy of activation and activation energy: the energy that an atomic system must acquire before a process (such as an emission or reaction) can occur

energy of activation (noun)	activation energy (noun)
the energy that an atomic system must acquire before a process (such as an emission or reaction) can occur	the energy that an atomic system must acquire before a process (such as an emission or reaction) can occur