My Dryer's manufacturer (Kenmore) lists that belt as P/N 661570.

I needed to replace the old one (since it was cracked) so I purchased
a new one on eBay. It came sealed in a bag manufactured by FSP. It has
the exact same number (661570) but... unlike the older (cracked) one,
it has only 4 ribs and measures only 1/4" wide.

The older one has 5 ribs and measures 5/16" wide.

Is this going to affect the machine in any way? Is it going to exert
unnecessary load on the motor, for example?

Thanks,
Sam