Following the assassination of Lincoln, the Army did not allow any pictures to be taken of him in his casket. Therefore, con artists stepped in to fill the demand. The top image was one of many that circulated purporting to show the dead President, but it is fake. Whoever the man is lying down, pretending to be dead, it is not Lincoln.
The bottom image is the only known authentic death photo of Lincoln. It shows him lying in state in New York City Hall, ten days after his assassination. It was taken by Garvey and Son, New York photographers. They later destroyed the original plate and all prints of it, except for one.
Links and References
"Rare Photo." (Feb 11, 1967). The Washington Post.
Brugioni, D. (1999). Photo Fakery. Brassey's: 36.