The Underground Railroad vs The Reverse Underground Railroad
Despite its name, the Underground Railroad was not underground or a railroad. The name is attributed to activities that needed to be done in secret, at night, or in disguise. Railway terms were used by those involved to describe how it worked. Routes taken were called lines, safe houses were called stations, and those who aided along the way were conductors and their runaways were known as packages or freight.
There was a vast network of people who helped fugitive slaves escape to the North and to Canada. It was not run by any single organization or person. Still, it effectively moved hundreds of slaves northward each year — according to one estimate, the South lost 100,000 slaves between 1810 and 1850. 
The Reverse Underground Railroad is a term used to describe the act of kidnapping free black Americans from Union states and taking them into slave states to be sold into slavery. According to the Complete History of Illinois published in 1876, “[I]n the majority of cases the poor ignorant blacks, by fraud and deceit, were inveigled [tricked] into a trip south on a flat boat, or other errand, and at some pre-arranged point on the river, they would be turned over to confederates, forcibly and rapidly taken to the interior and there sold into slavery”.  The 2013 film, 12 Years a Slave, is an example of the type of entrapment that many free black Americans were subjected to during that era.