Sergeant first class and Sergeant major

Sergeant first class noun - A sergeant in the Army above the rank of staff sergeant and below master sergeant.

Sergeant major and sergeant first class are semantically related. In some cases you can replace phrase "Sergeant major" with "Sergeant first class", this phrases are similar.

Sergeant major noun - A noncommissioned officer serving as chief administrative officer of a headquarters unit of the Army.

Sergeant first class and sergeant major are semantically related. Sometimes you can replace phrase "Sergeant first class" with "Sergeant major", this phrases are similar.