“Dialog” refers to instructions in a computer screen box. “Dialogue” is written conversation.
Will “dialogue” become “dialog”?
The sticklers for spelling will tolerate “dialog” in computing terms, as in the pop-up box asking you for information before you continue (“dialog box”). However, when two or more people are conversing, that should be “dialogue.”
According to www.thefreedictionary.com/dialog, the shorter word is a variant of “dialogue.”
“Dialogue” is the preferred spelling in www.dictionary.com, with “dialog” listed second.
Merriam-webster.com/dictionary sends the searcher to “dialogue” and offers “less commonly dialog” as a variant.
Collinsdictionary.com/dictionary refers to “dialog” as the American version, an “alt. sp. [sic] of dialogue” (alt. sp. = alternate spelling), listing as its source Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by Houghton Mifflin Harcourt. All rights reserved.
Other sources consider the longer version to be British and the shorter one more American. The simple fact is that sometimes spelling changes. “Catalogue” became “catalog.” (Even my spell checker agrees.) “Dialog” just doesn’t seem to have made the official change yet.