What is the difference between a single wall tip and a double wall tip on the magnaflow?

 

This is the only thing I could get off of Magnaflow's website...

"Polished Stainless Steel Double Wall Tips have a big look even with a smaller core. They stay cooler and resist discoloration. A great choice to complete your custom exhaust."

And then...

"Polished Stainless Steel Single Wall Tips really accentuate the rear of the vehicle. Use as single or double them up for a cool dual look. A great ride deserves stainless steel tips."

Source -> www.magnaflow.com

 

Thanks alot!