obligation vs commitment

In the subprime mortgage debacle, lenders lost the ability to estimate the extent of [their obligations] and the indebted to understand the implications of [their commitments].

Boy . . . I would say that the lenders have a commitment (to honor the loan) and the indebted should understand the implication of their obligation (to pay back the loan)

In any thesaurus, the fact that two words are listed together does not make them equivalent. English is full of nuance, and the reason thesauruses exist is that two words, even though they share a definition, are not exactly equivalent; one will work better than the other in a given situation.

Here, despite what sullyfish says, the lenders have an obligation to their investors to get the money back from the people they lent it to, with interest. Poor estimation of that obligation leads to the inability to satisfy their investors and the loss of their ability to do business.

The borrowers (the indebted) have made commitments to pay back the money, and the implications of those commitments (or failure to meet them) include loss of credit rating, loss of the collateral they used to borrow with (in the case of a home mortgage, you can lose the house and still be obligated to pay money to the lender), and bankruptcy.