While a tax deduction reduces taxable income, a tax credit reduces your tax liability dollar for dollar.
The General Business Credit (GBC) is made up of a number of separate credits specifically included by law in what is called the General Business Credit. In other words, the general business credit can be just one or more than one of the many available credits. Each separate credit is computed on a form for that particular credit.
There's a number of credits included in the General Business Credit. Here's a list.