The most notable difference are my clothing and sleeping gear.
Other than that I carry my main tools (knife, axe and a saw) and 3 piece cooking kit (pot, pan and a cup) with me all year around.
Choice in food items seems to remain mostly the same with the exception of meat. I tend to eat less meat in hot summer days (needless to say that in summer time uncured meat spoils fast).
Other noticeable difference in food choice comes from the long winter nights. Filling them with cooking experiments gives me something to do.
If I had the means, I would buy a hot tent for winter camping but I find the 3x3 tarp is enough for me in all seasons.
Inside the (3 season) sleeping bag goes my wool blanket and if needed, I wear my thick wool trousers and wool tunic too as a short term solution. In summer time, a wool blanket is often enough but the summer night might sometimes get chilly.
Being said that, I am saving up for a proper winter sleeping system.
I find the summer time to be the most difficult time to be out. If the temp is more than +20C it is too hot for my taste. The bugs and lush grass are another nuisance.
I try to choose a more windy camping spot, smoke them out (does not really work that well) or in rare occasions I use the inner tent of a cheap nylon tent under the tarp.
I have to say, I do not like tents and rather sleep under open skies. While the tarp gives me shelter from the rain, it also gives shelter to the mosquitoes.
Overall, I try to strive towards carrying as little as possible and having the skills to provide myself what is needed.
