Thank you therealjoeblow for your insights on yearly updates. I contacted Cannondale customer support, and for the 2017 Bad Boy models they have done a re-design. Below are the pictures of Bad Boy 4 2016 and 2017 models they sent me for comparison. The 2017 has a lefty fork, top tube has a forged reflective logo in the indentation, and other reflective graphics around the frame.

For differences on other components, here is what I can find:

Hubs:
2016 Cannondale C4, disc
2017 Cannondale Urban, 32 hole

Pedals:
2016 Cannondale Urban platform
2017 Cannondale Urban 6point3 Composite

Rear Cogs:
2016 Shimano, 8-sped: 11-32
2017 Sunrace CSM558, 11-32, 9-speed

Other than that everything else is the same.

Because I only ride on flat and easy paved bike routes, I may not want lefty fork in 2017 model to avoid maintenance hassles. And, being a newbie, I don't think I can feel the difference in upgraded components.
I have attached pictures below and, please, let me know other pros/cons between the two. Thanks again for your efforts in helping.

2016 Bad Boy 4 model:

2017 Bad Boy 4 model: