Secure Loan vs Unsecure Loan.
A bank loan typically appears on one's personal and business credit reports. Some loans would even require collateral such as being secured by one's home. Such loans also appear as liens on ones business. Merchant cash advance money does not appear on one's credit nor as a lien on one's business. Also, since the loan is not apparent to other creditors ones debt-to-income ratio is unaffected unlike with a bank loan.

Flexible vs Inflexible Payback.
Bank loans are paid back with the same payment each month. If you miss a payment because of a poor month then your credit suffers and you are likely to face fees and penalties. With a merchant cash advance the money typically comes back as a percentage of ones income and so would go down as your income falls. Therefore there is no chance of penalties nor credit damage.

Loan Cost.
Bank loans typically have significant origination and other fees tacked onto the loan amount. Moreover, business loans are likely to be high interest, often over 20% APR. If you take the full term to pay off the loan you are likely to pay the debt off 2 to 4 times over. The bank loan may have a prepayment penalty to prevent you relief from paying huge amounts of interest. There is also the risk of additional penalties. With merchant cash advances you will pay the debt off faster and with much less fees than paying back a traditional loan.