In the Parallels pop-up menu of the Resource palette, you'll find no less than three parallel databases dedicated to the gospels. In a recent comment on the blog, someone asked for an explanation of the differences between them. So here goes:
The Parallel database entitled Gospels is based on Kurt Aland's Synopsis of the Four Gospels, first published in the mid-1960's. Aland's Synopsis is, I believe, the standard reference for Gospel parallels. (At least, it's the one I used in college and seminary—and isn't that how all of us really decide what the "standard" reference works are?)
The Parallel database entitled Harmony is based on A.T. Robertson's A Harmony of the Gospels, and reflects a general tendency to harmonize the Gospel narratives.
Finally, the Parallel database entitled Synoptics is based on Huck and Lietzmann's Synopsis of the Three Synoptic Gospels. This synopsis was published in the 1930's and was the basis of Aland's Synopsis.
In general, Harmony and Synoptics tend to place larger passages in parallel, while Gospels tends to focus on smaller units. Likewise Harmony is more explicit in its attempts to reconcile Bible difficulties. For example, Robertson lists two occasions when Jesus cleansed the Temple—the first described in John and the second recounted in the Synoptics. Aland, on the other hand, simply places all four Gospels' accounts of temple cleansing together, leaving the reader to sort out how any differences among accounts are to be understood.
I hope that helps you understand the differences among the three Parallel databases which deal with the Gospels. Perhaps someone more familiar with these three synopses can offer more specific details.
By the way, if you want to get publication information about any Accordance module, don't forget to select About The Text from the Accordance menu.