I am very confusing when people and media use different words to describe about Bitcoin.
They can use words like
Virtual currency
Digital currency
Cryptocurrency
Electronic cash
I am very confusing with words like "virtual currency" but I don't know what is a best word to use to say about Bitcoin.
All the words you have listed are all fitting when explaining what is bitcoin. The these words are connected together to mean same thing. You can chose which you fell convenient with it will still be the best.
Read this for more clarification.
A quick introduction to Bitcoin. LEARN ME A BITCOIN.