Smaller ship, more need to build the idea that they were family (something Janeway excels at) since they were quite likely to never see their families again. The Enterprise was a like a huge office building doing the work of a big corporation. Voyager was like a small business with an exciting vision for the future. Budweiser vs a craft beer.
Simple things like the actors standing closer to each other than they do in TNG. Far more humor, less taking itself seriously. Liveliness. I find a lot of TNG scenes fairly stiff whereas with VOY you get the EMH's hyperbole, Janeway's touching everyone and very expressive face, Neelix bouncing around.. they had some excellent actors who interacted with a lot of body language, playing off each other rather than reciting lines.