Key terms are typically words that will come up a lot in a unit or a text. It’s more like a vocabulary related specifically to whatever it is you’re doing. High-use academic words, however, are words that are used a lot in a general academic setting, like a university or an academic journal.
Context clues provide further information about a word or phrase that helps readers understand its meaning. These clues offer insight - either directly or indirectly - into the portion of text that's difficult to understand.