Welcome to the forum!
Regarding your request, well, none of them are Canons. Nikon products, such a the D3100, are made by Canon's primary competitor, Nikon, itself. That being said, most wedding photographers used DSLR camera, and both Canon and Nikon do make good DSLR cameras. With some level of skill, even an entry-level DSLR, such as the D3100, or one of the comparable Canon Digital Rebel series, could successfully take a range of photographs normally associated with being a wedding photographer, with the task of preserving the memories of the occasion for the brides and groom, and their families. If you are simply a wedding guest, who wishes to record some images, the task is less demanding.
Keep in mind that a flash may not be allowed during the ceremony! Professional wedding photographers tend to own lenses with wide apertures, to enable more light to enter the camera in less time, which lessens the need for flash. These lenses are not inexpensive, but they do mount on the entry-level DSLR cameras as well as the larger, heavier DSLRs associated with pro photogrphers.
Professionals also have advanced flash units and accessories that soften and direct the flash, which is a far different effect than firing the light directly into the faces of everyone.
Your post, however, specified "weeding" rather than wedding. If I wished to photograph gardening or farming activities, well, I would think a DSLR to be an excellent choice for that, too.
Outdoor photography does not require the wide-aperture lenses that wedding and event photographers would use indoors.
Having said all of that, I am not a wedding photographer, as that is a rather specialized endeavour, so I will let others provide further, specific information.
Lastly, I know nothing about the Panasonics you mentioned, so can be of no help in that regard.