One verb can produce different kinds of nouns. With the root ḍ-r-b:
Word / formMeaning / explanation
ضَارِبٌa person who strikes: active participle.
مَضْرِبٌa source-pattern place or time of striking: noun of setting.
مِضْرَبٌan instrument for striking: instrument noun.
The agent performs the action, the place/time noun gives its setting, and the instrument is the object through which it is performed. These are not interchangeable meanings.