[The Saucepan Man]

I am currently reading the Hobbit to my daughter and we are both enjoying it immensely. Clearly, given that it is primarily a book for children, the style is very different from that of LotR. It is therefore not surprising that the Elves of Rivendell and Mirkwood and the Dwarves of Thorin's company are portrayed differently than their counterparts in LotR. As others have pointed out, this can be explained by reference to the different attributed authorship of the two books: Bilbo in the case of the Hobbit and Frodo and others in the case of LotR. Bilbo had good reason to portray Thranduil's folk unsympatheticaly and the Dwarves as slightly ineffective, whereas Frodo, Sam and co clearly regarded Legolas and Gimli as valiant and heroic companions.

Having said that, and notwithstanding the difference in style, I am not sure that there are any real factual discrepancies between the two books. Taking each of the examples given:

... the giants in the Misty Mountains ...

There is nothing in LotR to suggest that Stone Giants were not resident in the Misty Mountains. Indeed, on route to the pass of Caradhras, Boromir and Aragorn seem to allude to them:

"We cannot go further tonight," said Boromir. "Let those call it the wind who will; there are fell voices onthe air, and these stones are aimed at us."

"I do call it the wind," said Aragorn. "But that does not make what you say untrue. There are many evil and unfriendly things in the world that have little love for those that go on two legs and yet are not in league with Sauron, but have purposes of their own ..."

Boromir certainly seems to think that the stones are being thrown at them, stone throwing being a past-time of Stone Giants, although Aragorn's reference is less clear since one would imagine that Giants too would go on two legs.

... goblins instead of orcs ...

Goblins and Orcs are of the same ilk, although Goblins seem to be smaller in stature:

"A bit low for goblins, at least for the big ones," thought Bilbo, not knowing that even the big ones, the orcs of the mountains, go along at great speed stooping low with their hands almost on the ground.

... evil elves (Thranduil) ...

Thranduil's folk were not evil:

But the king, when he received the prayers of Bard, had pity, for he was the lord of a good and kindly people ...

... or the desert wyrms Bilbo talks about in the east.

Smaug was, I think, said to be one of the last of his kind. That does not preclude the possibility of other Dragons (ie Wyrms) residing in the deserts of the east. Or, as has been noted, they might simply have been a Hobbit myth.

So, I don't see any factual discrepancies. Just a difference in style. And personally, I love all the connections between the Hobbit and LotR, such as Gimli being Gloin's son, Legolas being Thranduil's son, the appearance of Sting and the mithril coat, and of course the central part played by the seemingly innocuous Ring that Bilbo picked up in the dark.