Is there any relation or link (by blood or legend or anything) between the dragon Glaurung, in The Children of Húrin, and Smaug in The Hobbit?
The answer is that it is not known. From Tolkien Gateway:
Exactly what this brood consisted of and, by extension, what Tolkien intended Glaurung's relationship to the rest of the dragons is unclear. The titles "Father of the Dragons" and "first of the urulóki" are also ambiguous in terms of whether Glaurung is a progenitor or simply the first to be created. His 'brood' could be all subsequent dragons, just one 'subspecies' or simply his immediate children. Certainly there is a case to be made that Ancalagon and the winged-dragons were a separate creation of Morgoth's, based on this passage:
[Morgoth] loosed upon his foes the last desperate assault that he had prepared, and out of the pits of Angband there issued the winged dragons, that had not before been seen —J.R.R. Tolkien, Christopher Tolkien (ed.), The Silmarillion, "Quenta Silmarillion: Of the Voyage of Eärendil and the War of Wrath".
There is likely to be no relation between Glaurung and Smaug since Glaurung was a wingless dragon and would have been no relation to the winged dragons which later served Morgorth. The only thing they have in common would be they both managed to have names in the Tolkien mythos. Very few dragons managed this feat.
Glaurung was a very powerful dragon, if not the most magical. According to Tolkien, he sired the rest of his race, or at least the brood of Urulóki, wingless fire-breathing dragons.
He was bred by Morgoth from some unknown stock and was the first dragon to appear outside of Angband. In 455 First Age Glaurung led the attack of fire that defeated the Noldorin Elves and their allies and broke the Siege of Angband in the Battle of Sudden Flame, the Dagor Bragollach.
Smaug was the mightiest dragon of the Third Age but his pedigree is unknown before his arrival at Mt. Erebor and the subsequent destruction of the Men and Dwarves below it.