Sergeant first class and Technical sergeant

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

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

Technical sergeant noun - A noncommissioned officer ranking below a master sergeant in the air force or marines.

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