The New Yorker has an intruiging review of the life and legacy of Alfred Russell Wallace. Since 2000, there have been at least five noteworthy biographies of Wallace, bringing greater historical and public attention to "Darwin's neglected double."
Beyond differences in our historical familiarity of the two men, Wallace and Darwin differed by social background, education, temperament, rhetorical skill, and methods (and certainly more). The article of course doesn't suggest that the two were intellectual equals, nor that we should all now be Wallacists, but it does shed light on how some of those differences (social backgorund, education, etc.) played out in the nineteenth-century.
One comment about class status:
For Darwin, and for other famous naturalists of the day, like Thomas Huxley and Joseph Hooker, the road to the Tropics generally ran through the finest universities and a post on one of Her Majesty's ships. For Bates and Wallace, who sailed for the Amazon in 1848, the jungle was their Oxford and Cambridge, as well as a source of income.
Another comment about training:
By the time Wallace was thirteen, the family fortunes had sunk so low that his parents could no longer afford to educate him. He was sent to London to board with a brother who was an apprentice carpenter. At the London Mechanics' Institute, one of several centers of higher learning for the working class, he heard lectures on Robert Owen, the Welsh social reformer, which turned him against the British class system, just as the pamphlets of Thomas Paine, and his brother's radical views, began turning him against the Church. He was soon packed off again, this time to live with another brother in the countryside north of London, working as an apprentice surveyor, but he took his radical notions with him.
Surveying allowed Wallace to spend his days outdoors, and a new phase of his life began. He discovered geology and botany, purchasing, in 1841, a pamphlet on the structure of plants published by the Society for the Diffusion of Useful Knowledge.
And, well, by the later 1800s, later in life, he was a spiritualist, anti-vaccination activist, believer in resurrection, and, after reading Edward Bellamy's "Looking Backward" in 1889, a socialist. Those things too may have something to do with his less-than-front-page historical reputation and significance.