tipped in= the fold-out map where one edge of the map is bound into the book.
general map= the overall map of Middle-Earth--usually included in The Fellowship of the Ring and The Two Towers.
Gondor map= the larger scale map of the Gondor/Rohan/Mordor areas--usually included in The Return of the King.
1954 map= the general map of Middle Earth that Christopher Tolkien drew, based on his 1943 map and J.R.R.'s own maps, that was included in the original publication of The Lord of the Rings.  This map is easily distinguished by the extremely long southwestern coastline of Umbar and Harad (with the inclusion of the Havens of Umbar); the labeling of the Icebay of Forochel such that it appears to be only a small portion of a large bight in the northern expanses of Middle-Earth; and the square compass in the top right-hand corner.
1980 map= When Unfinished Tales was being prepared for publication, Christopher Tolkien redrew and revised his originally published general map of Middle-Earth to make various corrections and clarifications.  This map is easily distinguished by the cropping of the Umbar coastline just above the Havens of Umbar; the relabeling of the Icebay of Forochel which adds a curved arrow to indicate that the entire water area is in fact the Icebay of Forochel; and a title plaque in the lower left-hand corner: "The West of Middle-Earth at the End of the Third Age."   The Gondor map was not redrawn.
quadrant map= in some editions, the general map is divided into 4 sections, each section filling a page.  On the preceeding page a copy of the entire map is squeezed onto a single page to serve as a guide to the sections.
CJRT= Christopher (John Reuel) Tolkien, third son of J.R.R. Tolkien and editor of J.R.R.T.'s posthumously published works.  These initials on the map pages indicate that the maps are Christopher Tolkien's renderings.  Christopher's maps all bear his initials (CJRT or CT).