The cycling pants are mainly used in modalities such as city cycling and extreme ones such as BMX, enduro, downhill or freeride. Apparently they look like ordinary pants, but technically they are a cycling garment adapted to this sport. Most bicycle pants incorporate a foam or gel pad in the crotch area that accommodates and cushions the cyclist from the vibrations of the saddle or from possible knocks against the frame.
Their cut is not as tight as for the cycling pants as the use of these pants is devised for greater comfort. Also their width is designed to be able to adapt to the protections underneath like, for example, knee guards, ankle guards, or an inner protection of the cycling pants.
In wintertime, their main use is for beating the cold and for waterproofing. But if the cold or rain were your main enemies for not cycling around town, then now you have no excuse. Combined with a good jacket and suitable gloves no one is going to stop you from taking to your bike in winter.
In summer most people go for the cargo pants model, with practical built in side pockets for storing personal items. On the other hand, you could always incorporate a cycling back pack into your gear and in this way carry your things around more safely and comfortably.