Let's leave the goofy ol.. sitcom... and move to the character.. developments..
Since the first season is full of whacky moments unless when the sequel is just about to get serious than before...
Familiar about "SHITS ABOUT TO GET REAL..." and 0-100% REAL QUICK scene..
They are almost like family. Both of them goof around while having a story "secretly" put in.
One of them gags with living daily in society and struggling with problems most of the time about the government, while the others gags with living in prison and being locked in one place (with the daily escaping attempts).
Some times I could relate the to of the anime together, the only difference is that Nanbaka goes to a story much faster (and it has less episodes/seasons of course) in comparison with Gintama. Also, Gintama is more vulgar in jokes than Nanbaka.