First Photo; 1880'ish. Most likely school boys at a prep military academy/school, sorta mimicing uniforms from the 1880 era. Not Civil War.

Second Photo: Both subjects are wearing what appears to be M1883 Enlisted fatique coats (five button front, no apparent service branch trim visible, which was present on the M1874) The subject on the right has an M1875 Infantry insignia on the front of his Kepi, still in use in the 1880's. US Infantry branch insignia changed from the bugle to the crossed rifles in 1875.

None of the subjects in either photo are of Civil War vintage. The photographic medium is on what is known as cabinet cards, which type ranges about 1885-1915 or so.
Frederick