Death in The Sims 4 is pretty much the same as it has always been, except that now, pushing your Sims into high levels of certain emotions can literally drive them to their death. Deaths in the game include dying from Laughter, Electrocution, Hunger, Anger, Fire, Embarrassment, Old Age, and more. The grim reaper also shows up with the modern tablet, plays around with it, and ends a Sim’s life.
One major change I noticed is how much harder it is to starve a Sim to death. Since Sims are much “smarter” now, even with autonomy turned off, the Sim desperately tried to survive. At some point he would go and have a snack in the kitchen, as he knew that he would die if he didn’t. Leave it to me to lock him in a doorless room…
Once your Sim dies, the Grim Reaper leaves behind an Urn (or tombstone if the Urn is taken outside), and takes off. You can converse with him afterwards, and he will even be visible in your relationships panel.
❗ SimGuruArgus mentioned that “Epic Poets” can write “epic sagas” and resurrect a Sim.
Also, you may have noticed that no ghost emerges from the dying Sim. When I asked developers to show me how to get a ghost to appear, they had no comment. Mix that in with the fact that I did not see one, and that leaves me with the impression that ghosts do not exist in the game right now.