There were differences. As far as we can tell from what has been preserved, the art of the scop was directed mostly towards epic poetry; the surviving verse in Old English consists of the epic Beowulf, religious verse in epic formats such as the Dream of the Rood, heroic lays of battle, and stern meditations on mortality and the transience of earthly glory. By contrast, the verse preserved from the skalds consists mostly of incidental verse contained in the sagas, often done up in the elaborate drottkvætt meter, and the ballad-like forms that form most of the corpus of the Elder Edda. Both, of course, wrote within the Germanic tradition of alliterative verse. The scop was a performer as well as a poet; he recited or sang his verses, usually accompanying himself on a harp or a similar stringed instrument.
In England, the calling of the scop was considered a worthier one than that of the skald. The word scop is related to modern English "shape"; the evocation of craftsmanship preserves the metaphor of the Greek word poet itself. The word skald has also been preserved in modern English: it became "scold." It seems that the Anglo-Saxons thought that the skalds were harping on things nobody wanted to hear.
See also: Old English poetry