The responses to my recent player survey suggest that some of them haven’t fully made the mental shift from D&D. I’ve played and enjoyed D&D for decades; but SW works better with a different play style. I wanted to explain the differences, and after some forum surfing, and reflection, this is what I came up with. Other insights welcome!
Ablative hit points vs sudden death: D&D characters are worn down gradually, over 4-5 encounters. In Savage Worlds, any blow in any fight can be lethal, and there’s no resurrection spell to bring you back.
Death spiral: D&D characters stay fully capable until they lose the last hit point. SW PCs see their capabilities degrade rapidly, wound by wound.
The GM effort per enemy to run an encounter is lower in SW than D&D, because of the simpler damage and condition rules, and because players control their allies, whether or not their characters do. This encourages bigger fights.
D&D characters start off weak, and improve dramatically as they level up. SW characters are more capable to begin with, but don’t improve as much later; arguably, they level off at the equivalent of 6th-8th level. There is thus no need for the monsters to get bigger and more dangerous as PCs level up, because even goblins remain a viable threat at all levels. Therefore, the multi-level range of monsters in D&D is unnecessary in Savage Worlds.
Savage Worlds isn’t very sensitive to differences in level between party members. This means new or intermittent players don’t get left behind.
Savage Worlds has no niche protection. In D&D, only a wizard can do wizardly things, only a thief can do thievish things, and only a fighter can fight well. In SW, there is no reason why a wizard can’t also be a competent fighter, stealthy, and able to pick locks. This means that effective parties can be smaller than in D&D, and as the party grows, it becomes harder for each character to have its own unique role in the group.
Update: As Umberto Pignatelli points out in the comments trail for this post, SW PCs tend to grow horizontally (broadening their niche and overlapping into other niches, but not getting overpoweringly good at any one skill or trait) while D&D ones grow vertically (getting much better at what their niche does).
Random encounters and traps in D&D provide experience and treasure for level grinding, and act as a “hit point tax” for entering parts of a scenario. Those are neither necessary nor desirable in Savage Worlds, as SW PCs don’t get experience for killing monsters, and don’t have hit points in the traditional sense.