Unless you head south for a chance at the grayling winter fishing means stillwater trout as the rivers round here are closed
The main differences are that the fish will usually be deeper in the water and more lethargic than in summer therefore the conventinal wisdom is to fish deep and slow. Usually winter is when lures become the norm however nymphs and drys can also be productive at times.
The best time of day to fish also changes from early and late in the summer to around midday in winter giving the fish a chance to warm up.
Michael