To tell apart action and descriptive verbs, think about how the verb relates to its subject. If the verb is indicating an action or something that the subject does, then it is an action verb. If the verb is describing a subject or a state that the subject is in, it is a descriptive verb. The distinction is fairly similar, though not completely similar (as you already mentioned!) to the verb/adjective distinction in English. You will gradually develop a feel for it as well. Until then, if you find yourself not quite sure if the word is an action verb or a descriptive verb, you can always hop over to the Korean Naver dictionary. Even if you can’t read the definitions, you can check to see if the word is labeled as 동사 (action verb) or 형용사 (descriptive verb).