These correspondences at least suggest that Revelation 7 advances the messianic army motif that Revelation 5 had begun. If so, then Revelation 7 parallels the Lion and Lamb vision of Revelation 5:5–6. In that earlier vision, John hears about the Lion of Judah but actually sees the Lamb slain. The point is that the conquering messiah conquers through his sacrificial death.
Revelation 7 describes two armies—the 144,000 and the multitude from the nations. These two groups are identified in various ways.
Some have argued that they represent Jewish and Gentile believers respectively (dispenational).Others see them as two visions of the same group (non-dispensational).
Probably the best way to understand the vision, however, is as a recapitution of the earlier vision of the Lion and Lamb in Revelation 5:5–6. A number of reasons lead to this conclusion.*