What's the physical difference between Hobbits and Dwarves?

Question

Yesterday (by now, after editing the question, a few days ago) I saw the wonderful third movie of "The Hobbit". I wasn't bored for a moment. Afterwards, while still thinking about the film, I was wondering what the physical difference between Hobbits and Dwarves is. I'm not asking about their origins or the language they speak or whatever. It's obvious they both look human-like and have about the same height. When you strip both of them of all their make-up and clothes (both of which the Dwarves clearly pay more attention to), i.e. when you look at both totally naked, I think the difference becomes much less. The dwarves are more massive (though I'm not too sure about that, because the dwarf that falls in love with an elf in the movie doesn't look that fat) and it is said in the answers I read that they have different feet (I've never seen a naked foot of a dwarf though) and Dwarves have more hair growing on them (I don't know if a Hobbit can grow a beard). It's not the same as asking the difference between a cat and a dog. The last two are much more different in their physical appearance than Dwarves and Hobbits. Cats and dogs are both mammals, and most (all?) mammals have four legs, a body, a head, a tail, and "wear" furry coats which they can't take of.

Are there more physical differences between Hobbits and Dwarves??

Answer 1

Dwarves and Hobbits have very different origins are two different species

Dwarves are creations of Aule, the craftsman.

in their beginning the Dwarves were made by Aulë in the darkness of Middle-earth; for so greatly did Aulë desire the coming of the Children, to have learners to whom he could teach his lore and his crafts, that he was unwilling to await the fulfilment of the designs of Ilúvatar. And Aulë made the Dwarves even as they still are

Hobbits were an offshoot of Men (most likely)

It is plain indeed that in spite of later estrangement Hobbits are relatives of ours [Men]: far nearer to us than Elves, or even than Dwarves. Of old they spoke the languages of Men, after their own fashion, and liked and disliked much the same things as Men did. But what exactly our relationship is can no longer be discovered.

Dwarves have beards, most Hobbits didn’t

The Dwarves were known for their long-beards, even dwarf women were known to grow beards, making them nearly indistinguishable from the men.

Not that I venture to disagree with Thorin, may his beard grow ever longer ...

... no Man nor Elf has ever seen a beardless Dwarf - unless he were shaven in mockery, and would then be more like to die of shame... For the Naugrim have beards from the beginning of their lives, male and female alike, nor indeed can their womenkind be discerned by those of other race, be it in feature or in gait or in voice, nor in any wise...

Hobbits were known to mostly be unable to grow beards

Dwarves speak Khûzdul and the Hobbits speak Westron

Dwarves has a secret language, that they rarely taught others and Tolkien himself hadn’t really fleshed out in any of his published works. Words like “Khazad-dum”, “Zirakzigil” etc.

Other differences

There are other differences between Dwarves and Hobbits. A primary one is stealth, Bilbo is brought along as a burglar in the Hobbit because of his greater stealth compared to the Dwarves; Legolas also makes a comment about the noise Gimli creates walking.

There are also a higher relative number of female Hobbits than female Dwarves, and instead of hairy chins, Hobbits have hairy feet.

Answer 2

There is already an excellent answer to this question by Edlothiad (I don't think I have ever managed to answer a Tolkien question before him). As the question lists language as one of the things that Hobbits and Dwarves have in common, I want to add a little about that.

The language that Hobbits and Dwarves have in common is not their own but rather Westron, the language that the Dúnedain brought from Númenor, which was known as the Common Speech as it was known to all races.

Hobbits

The Hobbits adopted Westron when they migrated north to Bree and the Shire.

It was in these early days, doubtless, that the Hobbits learned their letters and began to write after the manner of the Dúnedain, who had in their turn long before learned the art from the Elves. And in those days also they forgot whatever languages they had used before, and spoke ever after the Common Speech, the Westron as it was named, that was current through all the lands of the kings from Arnor to Gondor, and about all the coasts of the Sea from Belfalas to Lune. Yet they kept a few words of their own, as well as their own names of months and days, and a great store of personal names out of the past.

_{The Lord of the Rings Prologue, Section 1: Concerning Hobbits
Page 4 (Single volume 50th Anniversary Edition)}

Earlier, when they lived in the Vales of Anduin, they spoke the language of the Men of those part. That explains why Théoden recognises the word hobbit when he first meets Merry and Pippin.

The Riders laughed. ‘It cannot be doubted that we witness the meeting of dear friends,’ said Théoden. ‘So these are the lost ones of your company, Gandalf? The days are fated to be filled with marvels. Already I have seen many since I left my house; and now here before my eyes stand yet another of the folk of legend. Are not these the Halflings, that some among us call the Holbytlan?’

‘Hobbits, if you please, lord,’ said Pippin.

‘Hobbits?’ said Théoden. ‘Your tongue is strangely changed; but the name sounds not unfitting so. Hobbits! No report that I have heard does justice to the truth.’

Merry bowed; and Pippin got up and bowed low. ‘You are gracious, lord; or I hope that I may so take your words,’ he said. ‘And here is another marvel! I have wandered in many lands, since I left my home, and never till now have I found people that knew any story concerning hobbits.’

‘My people came out of the North long ago,’ said Théoden. ‘But I will not deceive you: we know no tales about hobbits. All that is said among us is that far away, over many hills and rivers, live the halfling folk that dwell in holes in sand-dunes. But there are no legends of their deeds, for it is said that they do little, and avoid the sight of men, being able to vanish in a twinkling; and they can change their voices to resemble the piping of birds. But it seems that more could be said.’

_{The Lord of the Rings Book Three, Chapter 9: Flotsam and Jetsam
Page 557-8 (Houghton Mifflin Harcourt; Single Volume 50th Anniversary Edition)}

Dwarves

Dwarves have a much longer history and while they use Westron to communicate with other people, they have their own language that they still use among themselves.

But in the Third Age close friendship still was found in many places between Men and Dwarves; and it was according to the nature of the Dwarves that, travelling and labouring and trading about the lands, as they did after the destruction of their ancient mansions, they should use the languages of Men among whom they dwelt. Yet in secret (a secret which unlike the Elves, they did not willingly unlock, even to their friends) they used their own strange tongue, changed little by the years; for it had become a tongue of lore rather than a cradle-speech, and they tended it and guarded it as a treasure of the past. Few of other race have succeeded in learning it. In this history it appears only in such place-names as Gimli revealed to his companions; and in the battle-cry which he uttered in the siege of the Hornburg. That at least was not secret, and had been heard on many a field since the world was young. Baruk Khazâd! Khazâd ai-mânu! ‘Axes of the Dwarves! The Dwarves are upon you!’

_{The Lord of the Rings Appendix F, Section I The Languages and Peoples of the Third Age
Page 1132-3 (Single volume 50th Anniversary Edition)}