Is there really a difference between a payday loan company and a check cashing company if they both cash checks for the customers? This particular payday loan company says that they have the customer sign a promissory note, but they still cash checks. Any opinions or a link to something that may have already be published?

As one of my accounting professors used to say "The words are trying to speak to you."

Check cashing is one thing.
Check cashing + lending money is something else.

Payday lenders are lending money. They often are not cashing any checks at all.

Check cashers are cashing checks. They often are not extending any credit at all.

They are both high risk accounts and would both require a high level of documented monitoring.

You might also want to review FinCEN Ruling 2002-2