One significant difference between a D&D Ranger and a Dunedain was the prohibition against associating in a group of more than three rangers. Sure, Aragorn preferred to operate alone, but when total war broke out, a large group of them (30? 50?) met him in Rohan, who he then lead through the paths of the dead and then onward.
Yes. I always found this strange. And what balance role did the "no more than 3 rangers" rule play?
Could scry with a crystal ball
Use of scrying devices like the palantir.
In LotR the reason Aragorn can use the palantir is because of his heritage. As the heir of Isildur and Elendil, the palantir's are rightfully his. Conversely, although Denethor is also a dunedain, his use of the palantir is part of what leads to his fall.
In D&D terms, the ability to use a palantir should therefore be part of a theme or bloodline feat, I think, rather than part of the ranger class - even an "Aragorn-style" ranger.
He got a bonus to surprise rolls
<snip>
He didn't get stealth skills
The stealth skills
were the bonus to surprise!
He didn't have an animal companion (save perhaps for a henchman)
At 10th level, he got 2d12 followers (which were faitfully loyal and did not count against the CHA allotment of henchmen), to be rolled up on a table in the DMG. Roughly speaking, the fewer the number of followers, the better each follower was. The best was a young copper dragon. It was also possible to get animals like bears, unicorns etc. And followers could also include henchmen types.
One ranger in my old AD&D campaign had 4 followers: a dragon, a brown bear, a human fighter and a human druid.
He got massive bonuses to damage "giant class" monsters which, despite the name, was nearly any humanoid in the MM.
I remeber this being very strong in Against the Giants, in conjunction with a +4 two handed sword and two-handed sword specilisation - 3d6 +4 +2 +10 for level + STR (18/01-50, from memory) for 3d6+16, or about 6 HD worth of damage on a hit - at 2 attacks per round for specialisation.
When I think dangerous man in the wilderness, "sword dancer" isn't really the first thing that comes to mind. I suppose if a drow became a ranger, with the drow's penchant for being graceful blademasters, that particular ranger would be good at two weapon fighting. But I don't see how it follows that this should be the only archetype for rangers who fight in melee.
In the Fiend Folio and Unearthed Arcana, drow had the ability to fight with two weapons without penalty. So Drizzt's two weapon fighting was originally a drow thing, not a ranger thing. I think it was 2nd ed that conflated the two.
EDIT: Alternatively, what [MENTION=7635]Remathilis[/MENTION] said.