You get what you pay for with cameras, Adam.

There are quite a few differences between my camera and yours. As aureolin has already said, the technical specifications of both cameras will reveal it all. I paid a fair amount for my Panasonic DMC-TZ40 when it first came out, and that does not even scratch the surface compared to my Nikon D5100 and I'm reluctant to use it in situations when it can be avoided.

The use of my Nikon D5100 is not limited to bus photography - the limits are endless. I am a bit of a fan of trains too, and do like taking the occasional photo of one. If the sun is at the right angle, I can get photos of trains flying down tracks at 100mph. I couldn't achieve that with my Panasonic, so I'm fairly confident that your Samsung wouldn't achieve that. I had a Samsung camera for a few days and I really wasn't impressed with it at all. The colours it was producing was appalling compared to what I had been used to with my Panasonic DMC-TZ30. I realised it was worth forking out the extra to upgrade to the TZ40 instead of using the Samsung.
I also produce more professional photographs if I get requests - obviously for a fee in most cases - and I would want the image to be completely perfect in this situation. Really, I honestly don't think anything other than a DSLR can get a really perfect photo.
I have used my Nikon for photography in school - for special events and for my Media Studies coursework. My TZ40 was good enough for that before, but I'm happier with what I have produced recently with the Nikon.

Obviously one you already know about is night photography. You've commented on one of my photos before saying that your camera doesn't like taking photos at night. It's next to no graft for the Nikon.