Size
The most obvious difference between the two species is the size. Pike, particularly northern pike, is among the largest of the Esocidae family. Pike can grow up to 59 inches long and 55 pounds. Pickerel is the smallest of the family, with the redfin pickerel species being the smallest followed by the chain pickerel. On rare occasion chain pickerel reach a length of 30 inches, with the average size being approximately 24 inches and only three pounds.
Body Type
As members of the same family both pike and pickerel have a similar body type. Both species are narrow fish, with greater length than either width or height, with pointed heads. The similar shape makes the two fish difficult to differentiate except that the pike is proportionally bigger in every way than the pickerel.
Coloration
Members of the pike species are generally dark gray in color with areas of lighter gray placed all across the body. The fins tend toward a striped texture displaying shades of black and yellow. Pickerel can have a lighter, more greenish hue, with yellowish patches. The fins are a lighter shade of yellow with dark ribbing. While the specifics of color vary by specific types of fish, generally pickerel are lighter than pike.
Muskellunge
Along with pike and pickerel the Escodiae family also includes the muskellunge species, also called muskie. Muskellunge are the largest of the three family species. They have the same body type. Like pickerel they are lighter in color than a pike, but the huge size difference between the species assures that a muskellunge can never be mistaken for a pickerel.