If you go off caffeine, you're drowsy for a few days, no big deal.
If you go off nicotine, you're condemning yourself to months or years of craving that never fully goes away: the physiological components of nicotine addiction are more or less permanent.
That's just off the top of my head. I wouldn't be surprised if there are detrimental dosage effects of nicotine that caffeine doesn't have.
Once I quit,I felt a bit uncomfortable like a very mild headache(almost background annoyance) for about two weeks and that was all there was to it. Now,I've never been addicted to caffeine even though I drink espresso shots daily for weeks and for a few more weeks might not drink any caffeine,so I have no frame of reference for comparison.
Stress does still cause me to be tempted but it's no worse than being tempted to eat fast food.