The Quenta Noldorinwa, also known simply as The Quenta, is the 'second' version of the Silmarillion, written in 1930.
This version of the Silmarillion holds especially importance as it is the only 'complete' version of the Legendarium that Tolkien ever completed to its end. Following on from 'The Sketch of the Mythology' This version of the Silmarillion also moves towards the final form of the story in almost all general terms.
However this version does differ significantly from the published Silmarillion. Most notable is that it is only about a quarter of the length of the published novel. This is largely due to Tolkien's often used method of expanding while composing. The end of the narrative differs in some respects, many names were still to be changed, and a few other narrative elements are slightly different or much more compressed, but by this stage the general history of the first age is largely complete.
Since it is the only version of the legendarium Tolkien ever completed, it also includes the last narratives of all of The Necklace of the Dwarves and of The Fall of Gondolin on which the published forms were based, albeit much changed in form in many cases.