For starters, Sir Gawain is not as noble as Beowulf. While Beowulf is presented as a great and noble warrior, we see Gawain as a bit of a proud hasty warrior that feels superior to anyone, seen in Arthur's hall when he just wants to fight without even thinking about it, and we can also see that he's very human considering how he made the mistake in Green king's court when he lied about the kiss and was scared. Beowulf on the other hand is an idealized warrior whose only mistake is in the end when his Hubris gets the best of him. The hubris wasn't a problem in his youth because his body and skill could follow his endeavors.
