explanation vs thought process

explanation and thought process both are nouns.

Word	Noun	Adjective	Verb	Adverb
explanation	Yes	No	No	No
thought process	Yes	No	No	No

As nouns, thought process is a hypernym of explanation; that is, thought process is a word with a broader meaning than explanation:

explanation: thought that makes something comprehensible
thought process: the process of using your mind to consider something carefully

Other hypernyms of explanation include cerebration, intellection, mentation, thinking, thought.

explanation (noun)	thought process (noun)
thought that makes something comprehensible	the process of using your mind to consider something carefully
a statement that makes something comprehensible by describing the relevant structure or operation or circumstances etc.
the act of explaining; making something plain or intelligible