Dell 5720 Verizon and Sprint, the same? Also, WiFi catcher, does it ever work?

I've got 2 questions and I figured it would be best to add them to one post.

Question 1: Are the Dell 5720 Verizon and Sprint the same? I really can't see a difference between the 2 and the FCC ID on them is the same so I'm kind of clueless as to whether they are the same or not.

Question 2: Does the WiFi catcher ever work? I've got a Dell Latitude D820 with the WiFi catcher set to only detect WiFi and I never get any light so I'm wondering, does it ever work or is it the fact that I'm using the wireless card from a Dell Mini 10 in this?

Thanks ahead for any answers.