What is differnce between Norton.com/latestnav and Norton antivirus

i bought a pendrive of hp and got a activation key for norton antivirus ,i want to know what is difference between

The file Downloaded from Norton.com/latestNav and Norton antivirus .I am asking this Because there is a huge difference of file size.

and also want to know If i download the trail version of Norton antivirus and Try to activate it the Redemption Key .Will It work?

Thanks in advance