Obviously Bitcoin price; the amount Bitcoin is worth at a particular time, and Bitcoin usage; the rate at which Bitcoin is adopted and used. The above phenoms surely has implications, one may be tempted to as; which is more important? The interesting fact is, price affects usage both positively and negatively. An increase in price attracts high usage, and vice versa. Conversely usage also affects the long term pricing of Bitcoin. Price has short term implications, usage and acceptance has long term implications. From the aformentioned, I can conclusively say; Price and Usage are phenoms that can influence the volatility of Bitcoin
I don't think we can differentiate between the two, as they are inextricably linked. Simply put, supply and demand for a good influence its value or price. Meanwhile, the usage of a good is one factor that increases demand for it. So, when we talk about Bitcoin, the same applies. I hope you understand my point. Additionally, you need to realize that Bitcoin is already widely used, and has the potential to become even more widespread, plus Bitcoin has scarcity, so you should know that it will be an added value for Bitcoin's price increase.
For reference, perhaps you need to read things regarding to our discussion this time :
investopedia.com - What Determines Bitcoin's Price?