/u/ThisOldHatte is correct: Confederate officer and enlisted. This photo hit the internet as part of the exhibit "Photography and the American Civil War" at the Metropolitan Museum of Art, April – Sept 2013.

‘Captain Charles A. and Sergeant John M. Hawkins, Company E, “Tom Cobb Infantry,” Thirty-eighth Regiment, Georgia Volunteer Infantry,’ 1861–62, by an unknown artist. (Photo by Jack Melton/Metropolitan Museum of Art)

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EDIT: direct link to museum webpage for highres photo:

In this quarter-plate ambrotype, Confederate Captain Charles Hawkins of the Thirty-eighth Regiment, Georgia Volunteer Infantry, on the left, sits for his portrait with his brother John, a sergeant in the same regiment. They address the camera and draw their fighting knives from scabbards. Charles would die on June 13, 1863, in the Shenandoah Valley during General Robert E. Lee’s second invasion of the North. John, wounded at the Battle of Gaines’s Mill in June 1862, would survive the war, fighting with his company until its surrender at Appomattox.