As nouns the difference between seg and skeg
is that
seg is (archaic) a man; warrior; hero or
seg can be (uk|scotland|dialect) a castrated bull or
seg can be segregation or
seg can be a metal stud or plate fixed to the sole or heel of a shoe to prevent excessive wear also known as a blakey or
seg can be sedge while
skeg is (nautical) a fin-like structure to the rear of the keel of a vessel that supports the rudder and protects a propeller.