Whitman: For issues cover dated February 1977 to around May 1979, Marvel produced non-newsstand editions that were sold mainly in packages. Some, but not all of these, were sold by Western and, because of the branding on the similar DC and Gold Key comics, are generally known as Whitman variants. For the most part they have a square diamond price and either a barcode or a white space where the barcode should be. Some issues from this time have the narrower diamond but it is not currently known if this means they were distributed differently or if it was simply because of the design of the original cover. There is definitely uncertainty between the end of the Whitman comics and the beginning of the Direct comics.
Direct: Starting with issues cover dated around April 1979, Marvel started producing non-newsstand editions to be sold in the direct market. For the most part they have a narrower diamond price and the barcode has a line through it (until February 1980 when they started putting a Spider-Man head and eventually other artwork in the UPC box area).
Direct Edition: In July 1993, Marvel started putting a barcode on the issues sold to the Direct market. They included the words "Direct Edition" in the barcode box.
Does this data need corrections? Become an editor.