We get this question a lot since I build a lot of these so I thought I would post some comparisons a there seems to be so much inaccurate information on the tops mainly because people have never seen them side by side, owned both, or its a sales person who is biased because its their job to represent their company. No problem with that, : just have to understand you are talking to a sales person likely rather than an installer/engineer when you talk to builders most of the time, they are just doing their job.
I have owned both, several times on my personal vans. To be fair both tops are nice...but they are VERY different each one has it's +/-'s. I personally like the CCV top because its way larger in every aspect (height, width, bed, windows), insulation option, and more larger windows, plus most importantly you can put a fan on it. However the SMB top is lower profile, opens up the entire van with out moving any panels, and has nicer interior finish.
SMB tends to be a bit less when spec'd the same, but make sure you are adding all the options to make it complete to compare true accurate prices. CCV's base price is everything all in (less top paint match if needed)
When I have had people see the tops side by side...they are blown away on the size difference inside, but its really in my opinion compromise between inside space, total height, fan option, and if you want the bed to totally lift up. Really not apples to apples.
Size Comparison (Photos cannot do justice to the difference inside)
Rigidity in wind or safety is different (given the CCV top keep C pillar intact)
Openings: (with panels removed or lifted)
Some other comments as well regarding use. Shades are a bit different; CCV has a zippered black out...and its black vs SMB you get some light in. The zipper corners in CCV are curved which makes them a bit easier to unzip vs the angled ones in SMB. CCV has a rear window as well and an insulation winter option for their tops. Again the are both nice in their own way...very different. This size difference however is huge...almost anyone can sit up in the CCV top, no way you can do this in an SMB...its just a lot lower. The sleeping width as well with the SMB is much narrower, with larger people you tend to hit the support bars...those few inches make a big difference if you are large or like a lot of room for your bed. To be transparent I prefer the CCV for its size and the fan; however its these things that also make the SMB one more attractive for others...compact and low profile SMB top as well as cost tends to be a bit less if you are comparing apples to apples in options.
Bed Dimensions for Sprinter CCV top, they do a Pop Top on a high roof, I have driven the van; its similar to having a high Aluminess rack on top of your van, its pretty high to get into, but if you have a large family...its an option that would work. Low roof bed dimensions: 54" x 80" High roof bed dimensions: 45" x 80" (due to the taper of van) Low roof - floor to pop top when top down - 75" Low roof - floor to bottom of bed boards - 66" High roof - floor to pop top when top down - 87" High roof - floor to bottom of bed boards - 78" SMB Bed Size: The mattress is in a form of a "T" vs a rectangle, you do notice the width a lot if two full size adults are sleeping, just like the CCV high roof top 45" width is on the narrow side for larger people. My teenage girls really noticed the width and height difference big time when we used a SMB Sprinter Top on our last big trip. They really did not like the smaller size of the top...its a pretty big difference. Sprinter 40″ (waist/leg width) 53″ (at shoulders, only, upper part of bed)
Some good pics for comparison of both tops up/down and compared to a high roof Sprinter.
With Tops Down
Side by Side (high roof sprinter, low roof sprinter with CCV top, Promaster with CCV Top)