A gerund is an "-ing" form that does the job of a noun. The present participle is an "-ing" form that may either be used to form the present progressive tense (to be + "-ing" verb) or to do the job of an adjective (e.g., the crying man). "He does nothing all day long. He eats and sleeps all day long." = He does nothing all day long, except (to) eat and (to) sleep. (If you wanted to use "eating" and "sleeping," then you would be using them as the names of activities, so therefore they would be gerunds.)

When a verb ends in -ing, it may be a gerund or a present participle. It is important to understand that they are not the same. When we use a verb in -ing form more like a noun, it is usually a gerund: * Fishing is fun. When we use a verb in -ing form more like a verb or an adjective, it is usually a present participle: * Anthony is fishing. * I have a boring teacher.