Though both end in "-ing," the present participle form of a verb is not the same as the present progressive aspect (also called the present continuous).
What They Are and How They Are Formed
What is a present participle?
A verb form with an "-ing" ending (for example, "tapping").
What is the present progressive aspect?
A form of the verb "to be" PLUS a present participle (for example, "is tapping").
How They Are Used
A present participle alone can't stand as the main verb of a sentence. For instance, "Sadie, tapping her cane to the music" is incomplete. In this example, "tapping" begins a present participial phrase that modifies the noun "Sadie." One way to make this word group into a sentence is by adding a subject and a predicate: "I remember Sadie, tapping her cane to the music."
A verb in the present progressive aspect may itself serve as the predicate of a sentence: "Sadie is tapping her cane to the music." The present progressive is used for ongoing actions--that is, for actions occurring at the moment of speaking and for actions that take place for a short period of time.
So, we could have a sentence that contains both a present participial phrase ("tapping her cane to the music") and a main verb in the present progressive ("is singing"):
- Tapping her cane to the music, Sadie is singing loudly and out of key.