Gandalf makes it clear to Bilbo that this is because of the elvish make of the blade. His sword, however, does not glow blue in the presence of orcs or goblins.
Neither does Thorin's.
The Book: There is explicit mention of both Orcrist and Glamdring "shining cold and bright" in the presence of goblins. Bilbo actually notices the glowing of his own blade after the glowing of theirs. Only then does he piece together that his sword must have been made in the same place as Thorin's and Gandalf's.
What difference does it make? As far as details go, this is about as minor as it gets. Showing Orcrist and Glamdring glowing would have been a nice touch, but otherwise would have contributed nothing to the story.
My Opinion: Alright, I know this makes me one of those people, but the sword thing really bothered me.
On the one hand, it was made pretty clear in the books that the swords glow. It's not super important for Orcrist and Glamdring to glow - unlike Bilbo's, where it's a necessary part of the story - but it's still a detail that is specifically mentioned, and one that should have been visually communicated in the movie. Like Gandalf's beard or pointy hat; technically neither are necessary for the character, and don't do anything to the plot, but they were mentioned in the book and deserve to be in the movie! Similarly, there's no reason not to have the swords glow.
On the other hand... it violates the movie's own internal logic! If only Bilbo's sword is meant to glow, for some reason, then you need to give us a reason for that. "It belonged to a sorcerer who cast a spell on it" or something. Saying that it will glow blue because "it was made by elves" would be fine if you didn't present two other swords, say they were made by elves, and not have them glow! If your movie is going to set rules, it has to follow them. Especially if they violate what's in the fucking book.