there is a big difference between "digital" and "virtual".
bitcoin is a "digital" currency or also known as "crypto" currency due to its usage of cryptography.
a virtual currency is virtual, like the currency that you use inside a game for instance.
https://en.wikipedia.org/wiki/Virtual_currencyLegally speaking, a virtual currency is a currency not backed by a government, but still used as an actual currency by people. So technically in-game currency isn't a virtual currency in this sense because it's not used outside of a game. But on practice the terms "virtual currency" and "digital currency" are used interchangeably by everyone, including bloggers, government officials and academics, so I wouldn't be too bothered if someone calls Bitcoin a virtual currency.