What we can extrapolate from this is fairly clear, if you dig into what he did not describe: the Ranger's footprints. Fact is, Aragorn is able to tell the stranger's footprints apart from the recent presence of Rangers because they donned heavy boots. Heavy doesn't always refer to weight, though in this case it could. That distinction here, however, doesn't give us any specific clues as to the Ranger's boots, unless we turn back to read only a few chapters prior:The Lord of the Rings: The Fellowship of the Ring; Book 1, Chapter XI, A Knife in the Dark, Pg. 184 wrote:"Sam and Peregrin had not been idle. ... Not far away they found a spring of clear water in the hillside, and near it footprints not more than a day or two old. In the dell itself they found recent traces of a fire, and other signs of a hasty camp. ... 'It is just as I feared, he [Strider] said, when he came back. 'Sam and Pippin have trampled the soft ground, and the marks are spoilt or confused. Rangers have been here lately. It is they who left the firewood behind. But there are also several newer tracks that were not made by Rangers. At least one set was made, only a day or two ago, by heavy boots. At least one. I cannot now be certain, but I think there were many booted feet.'"
Sup·ple ˈsəpəlThe Lord of the Rings: The Fellowship of the Ring; Book 1, Chapter IX, At the Sign of the Prancing Pony, Pg. 153 wrote:"His legs were stretched out before him, showing high boots of supple leather that fitted him well, but had seen much wear and were not caked with mud."
adjective
1. bending and moving easily and gracefully; flexible.
Now, this isn't a new quote to us, but all it talks about are Aragorn's boots. If we put two and two together, however, what we're seeing is that Rangers, being skilled travelers and huntsmen as told us by Gandalf [assuming Aragorn is the rule, rather than the exception (Ch. II, Shadow of the Past)], have almost universally accepted flexible, softer-soled footwear as their primary and/or preferred means of footwear. In short, they are wearing something such as a turnshoe/turnsole with a high upper, in stark contrast to the footwear worn by the mysterious visitors to the grassy dell at Weathertop, who we are left to assume were the Black Riders. Given the nature of their travel, being on horseback, it is reasonable to assume, then, that they were wearing riding boots, likely with a heel for keeping a foot securely in a stirrup. Such a distinct track would lead us to this stark contrast, and (in my opinion) lends credence to the idea of Turnshoes being a mainstay for the wanderers about Bree.