Mr. Zumwalt,
There are quite a few differences. First off they are 2 different projects. But you knew that. But, with that said, they both operate in different ways.
I’m sure this is a Fritzing biased site, but what DO I know…
Kicad is still heavily developed and all that development is done by CERN. I’m not sure Fritzing holds a candle to their flame as far as funding…
Fritzing is still in Beta, Kicad is not.
Fritzing works seamlessly in all modes, Schematic to PCB, whereas Kicad does require a netlist export. So kicad is more of a multiple program all based-in-one solution.Those programs are; Eeshcema, pcbnew, GerbView, a schematic library editor, and a PCB footprint editor.
Fritzing relies heavily on the usage of .SVG files. Good for me because I can use my favorite vector graphic program to make part foot-prints. So if you’re a fan of vector graphics Fritzing might be a popular alternative.
Kicad has a more robust toolset @ a cost of all loosing all intuitive learning aspects. Might as well have the manual next too you @ all times. Kicad supports multi-layer board design, while Fritzing does not. I could have seriously dove in here, but I’m not wasting my night…
I’ll sum it up with ease of use. Kicad is far more in-depth and complicated to use. Fritzing’s initial target market was hobbyist, learners, and makers.(forgive me if I left anyone out) Designed to get their feet wet without convoluted madness going on.
I personally have both installed on my system, I’d also recommend you do the same. This way you can use both and decide for yourself what is best suited for your particular needs. We can swing our you-know-whats all day long… But in the end, what matters? A final product. There is no right or wrong way for 2 layer basic board production. But this is a simple choice if you need more then 2 layers…
Have fun! Best of luck to you