There's a big difference. Moreover, people quit smoking all the time, often without any help whatsoever. There are more ex-smokers than smokers walking around. It may be hard to stop, but it isn't impossible. People choose to start smoking.
People choose to keep smoking.
When it's important enough to them, people choose to stop smoking. The Medicare suits are even more ludicrous. The theory is that the ailments suffered by elderly smokers drain the states' Medicare coffers. So the deep-pocketed tobacco companies should pay. When people get heart disease, states don't sue beef cattle farmers or meat packers.