Home-made ginger beer is a carbonated, slightly alcoholic fermented beverage that is prepared with the help of a so-called ginger bug.
This ginger bug is the culture used to make ginger beer. It is a kind of starter liquid that is prepared with fresh ginger and sugar. It contains a small microbial ecosystem of different yeasts and bacteria and ensures that your ginger beer ferments.
> The ginger beer is the fermented drink that you can drink.
> The ginger bug is the culture/brewing liquid used to ferment the ginger beer.