Two discount giants tell different stories today, underscoring the wishy-washiness of this year's holiday shopping outlook.

Things are looking up at J.C. Penney(NYSE: JCP), while the world's biggest retailer, Wal-Mart(NYSE: WMT), said last week's sales weren't as strong as it had hoped but remain within range.

Penney's sales and demand are ringing up ahead of its expectations so far this month -- even more evidence that the company's turnaround plans are solidly progressing. It expects a low single-digit comps gain for December and anticipates more customers will realize "it's all inside" for the last-minute shopping crunch this weekend.

Wal-Mart's week didn't go as planned, however, with sales trending at the low end of expectations. It attributes the relative weakness to customer procrastination and looks forward to a flood of shoppers as Christmas approaches. The retailer isn't budging on its outlook, and still predicts comp sales will increase 3% to 5% for December.

What will the end story be? Will Penney's results stay strong? Will Wal-Mart's aisles fill with people come next week? The University of Michigan's consumer sentiment index painted a rosy scene of shoppers apparently feeling more festive this month than last. Whether those cheery thoughts will translate into actual buying remains to be seen.

Stay tuned.