Some Jewish history explains that neither Enoch nor Elijah had sinned, and accordingly they did not die. The traditional expectation and view of Elijah were different from John the Baptist.
First, Elijah was someone who was always working for the church.
According to one Jewish historian “from the time of his appearance in the days of Ahab to that of his return as the forerunner of the Messiah” Elijah’s relationship to Israel is represented “as continuous, and that he is almost constantly introduced on the scene, either as in converse with some Rabbi, or else as busy about Israel’s welfare, and connected with it.” ('The Life and Times of Jesus the Messiah', by Alfred Edersheim)
With respect to his final ‘coming’ he was supposed to come very closely before the Messiah. However Elijah was not supposed to come in ‘spirit and power’ but in person, in his flesh. He was to have a similar but lesser role to that of Messiah. For example, just as with the Messiah (see this post for what they expected of Messiah) Elijah was “to appear, then to disappear and to appear again in the wars of Gog and Magog” (Seder Olam Rabbah.7.). But after Elijah would discharge his peculiar functions along side of the Messiah, everything else fell under the work of the Messiah only.
Regarding Elijah’s close relationship with Messiah he was to appear suddenly, not on a Sabbath or feast-day, possibly “three days before the Messiah” (Yalkut, vol. 2)
This verse leads to an interesting expectation:
How beautiful on the mountains are the feet of those who bring good news, who proclaim peace, who bring good tidings, who proclaim salvation, who say to Zion, "Your God reigns!" (Isaiah 52:7)
On the first of those three days, “Elijah would stand on the mountains of Israel, lamenting the desolateness of the land, his voice being heard from one end of the world to the other, after which he would proclaim: ‘Peace’ cometh to the world; ‘peace’ cometh to the world! Similarly on the second day he would proclaim, ‘Good’ cometh to the world; ‘good’ cometh to the world! Lastly, on the third day, he would, in the same manner as the two previous days, make proclamation: ‘Jeshuah6423 (salvation) cometh to the world; Jeshuah (salvation) cometh to the world,’” ('The Life and Times of Jesus the Messiah', by Alfred Edersheim)
Conclusion: Although the differences are substantial, it further conforms that prophecy was never meant to be absolutely understood, but did provide a certain level of expectation that would be satisfied and more fully explained, when the event actually took place.
For understanding the conflicting ambiguity and uncertainty of prophecy my recent addition to this post.