Looking for a bit of information. I have a friend who is rather large who would like to take up cycling. He is currently loosing weight but due his size feels a recumbent bike would be the best choice for him at the moment. He would like to know if the quality of exercise is different riding a road bike vs. a recumbent.

it's up to the exercisor to determine the quality of the exercise. seriously, i would recomend a standard road bike. if that's not possible a recumbent would provide a similar training effect to a road bicycle

Exercise is exercise; different leg muscles, same heart and lungs.

With bents you don't get saddle sore or wrist, neck or shoulder strain, which makes an enormous difference to your comfort. Against that, while you're learning to ride one, the sudden stabs you night make at the ground with a foot, to save you from toppling over, could be jolting to heavy people (depending on your model).

A bent is not much harder to learn on than an upright, but an upright lets you push off with a foot still near the ground, and glide to a halt with both feet down if necessary; the bent has your feet further from the ground (again depending on your model). The first few days can be awkward, after that it's plain sailing.