Is a canopy or a pergola better over a backyard deck?

That really depends on both your budget and the intended purpose. Awnings or canopies tend to run less expensive than pergolas. A canopy will block a lot more sunlight and precipitation. read more

The Pergola doesn't really shelter you from rain or sun, while the Canopy does. However a pergola with a side panel like in your picture (some only have a top panel) does shield you from wind more than the Canopy would. read more

A canopy patio awning is a fabric-roofed structures supported by a freestanding, rigid frame that’s bolted to your deck. The frame becomes a permanent part of your deck, and you can either leave the fabric up year-round or remove it seasonally. read more