A Halberd, or also called a Halbert or Halbard, originated in the Middle Ages and continued to be used as a ceremonial weapon. In the 17th & 18th Centuries, it was the sign of a sergeant of infantry, thus some state militia units used them just prior to the American Civil War in 1850s. It was discontinued in the British Army in 1792 and replaced by the Spontoon.
A Pike was a long version of the spear. In the British Army the pike was 18 feet long and used to repel cavalry and infantry charges. It was discontinued in the British army during the reign of Queen Anne. It preceeded the Halberd and did not have a axe blade.