Diesel has more energy per unit volume, more energy per unit weight, and has potential for more efficiency because of his higher compression ratio.
If you heat the fuel before you inject it, and use a supercritical injector, you can get 20% improved efficiency.
Most engines do ‘negative work’ by compressing burned fuel (injection is before top dead center). A supercritical injector can remove that negative energy. One company that developed a patented supercritical fuel injector is
Transonic Combustion. No I don’t own stock. The above information is available off its web site.
I know diesels can be hard to start in winter. When I worked for a truck rental outlet, sometimes we had to use additives to keep it from gelling in the cold weather. My father was in Korea from 1955/56 during his hitch with the Army, he remembers starting diesel trucks on gasoline, let them idle for 30 seconds to a minute to warm up and then shifted the fuel lever to diesel and they were good to go.