If you've seen the same grid-based simplification method called both a "Karnaugh map" and a "Veitch diagram" in different textbooks, that's not a mistake — both names describe the same underlying idea, and the naming split comes down to history rather than any real technical difference in how the tool is used today.
Where the two names come from
Edward Veitch published a diagram for simplifying Boolean functions in 1952. The following year, Maurice Karnaugh published a refinement of the same underlying idea, using a cell arrangement based on Gray code ordering, which is what gives the map its now-standard property that every adjacent cell differs by exactly one input bit. That specific property — the one every grouping rule on a modern K-map depends on — is generally associated with Karnaugh's version of the layout, which is why "Karnaugh map" became the dominant name in most textbooks and course material published afterward.
Does it matter which name a textbook uses?
Not for how you actually use it. If a course or textbook says "Veitch diagram," it's referring to the same grid-and-grouping method covered throughout this site — same adjacency rules, same grouping strategy, same minimization goal. The name is a historical artifact of which publication a particular curriculum's material traces back to, not a signal that a different technique is being taught.