As with many authors from this period, we have limited knowledge about the authors of these poems. One very key distinction is that the author of Beowulf is far, far younger than the story he tells. The old Nordic story of the man from Geats is especially affected by its distance in time from the author, since while Beowulf is a pagan hero, the author is a Christian. This creates a strange thematic tension in the play, where the author honors the hero as a cultural icon while also adding Christian themes into the story.
While the Arthurian legends absolutely predate the Pearl Poet, Gawain's place in cultural memory is undoubtably linked to both Christianity and romantic chivalry. This creates less distance between the story and historical context of the composition. I should note, though, that certain parts of the poem (the Green Knight for instance) do have a great deal of pagan influence.
A little more is known about the Pearl Poet than the author of Beowulf. For instance, there are a few well-regarded theories about this person's identity. This was most likely a man of the noble class, in roughly around the same time as Chaucer. Many speculate that the Beowulf poet did not so much as compose the poem as write it down upon hearing it from oral tradition. Some suggest that the Beowulf poet might have been a clergyman.