The main difference between business credit (also known as corporate credit) and personal credit is that personal credit is all based on the FICO of the owner of the business.  Business credit is based on both the PAYDEX score of the business and the FICO of the CFO of the business.

PAYDEX is like the FICO of a business it ranges from 1 to 100.  The optimum range is near 80. 

Personal Credit affects you FICO score.  Business Credit affects the business's PAYDEX score and has no effect on your FICO.

One of the common misconceptions is that you don't need to personally sign for a business line of credit.  Maybe 5-10 years ago when lenders were tossing money out the windows for businesses that might have been true.  Not any more.  The main difference is that the signer will be the CFO not the business owner.  Also, while the CFO has to sign for the line of credit to open it, if the company performs well then in about 18 months the CFO can generally be taken off the line of credit and the LoC will then be completely on the company.

The interest rates can be very different.  Most personal lines of credit have rates of prime plus 2% - 4%.  A properly set up and managed corporation or LLC can get rates under 6% even in today's market.