My (hopefully) comprehensive list of printing notes from the 3rd Plus through 5th. Asterisks indicate a change from the immediately previous printing, question marks mean I'm not sure. NEW: Plus marks indicate a change since the 4th Alpha, but not different from the immediately previous printing, to help gauge cumulative change. If you note any errors, let me know.
3rd Plus
*Front Cover: *Yellow-banner reads "ADVANCED D&D"; *black outlined letters; Wizard logo; rough textured
Flyleafs: Red
Pages: smooth
*Stitching: approx 5/8", 17 or 18 stitches
Rear Cover: No ISBN
Spine: Early red-letter version; wizard logo
Copyright Page: (R), "3rd Edition, December 1978"; full justified "Inquiries..." lines;
Giants: 21-30
Hydra: Larger picture
Vampire: "per turn of immersion"
Page 111: right-justified prices;
DMG listed as "Future Release"
Page 112: right-justified prices; "booklet only $4.00" STAR PROBE; "booklet only $5.50" STAR EMPIRES; "send $2.00 for our catalog."; "potpourri" Gencon ad
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4th Alpha
Front Cover: Yellow-banner reads "ADVANCED D&D"; black outlined letters; Wizard logo; rough textured
Flyleafs: Red
Pages: smooth
*Stitching: *approx 1", 11 or 12 stitches
*Rear Cover: *ISBN
*Spine: *New, completely updated spine
*Copyright Page: *"TM"; *"4th Edition, August, 1979"; *added Jean Wells credit; *center justified "Inquiries..." lines; *ISBN added; *Giants: *19-25
Hydra: Larger picture
Vampire: *"per round of immersion"
*Page 111: *No prices; *DMG not listed as "Future Release"
*Page 112: *No prices; "booklet only $4.00" STAR PROBE; "booklet only $5.50" STAR EMPIRES; *"send for our catalog."; "potpourri" Gencon ad
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4th Beta
*Front Cover: Yellow-banner reads "ADVANCED D&D"; black outlined letters; Wizard logo; *smooth textured
Flyleafs: Red
Pages: smooth
*Stitching: *approx 3/4", 16 to 18 stitches
Rear Cover: ISBN
Spine: New spine
*Copyright Page: "TM"; "4th Edition, August, 1979"; Jean Wells credit; *"Distributed to the book trade in the United States by Random House.."; center justified "Inquiries..." lines;
Giants: 19-25
*Hydra: *Smaller raised illustration
Vampire: "per round of immersion"
Page 111: No prices;
DMG not listed as "Future Release"
*Page 112: No prices; *No prices next to STAR PROBE; *No prices next to STAR EMPIRES; "send for our catalog."; "potpourri" Gencon ad
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4th Gamma
+Front Cover: Yellow-banner reads "ADVANCED D&D" and black outlined letters; Wizard logo; +smooth textured
*Flyleafs: White
Pages: smooth
*Stitching: *approx 7/8", 15 stitches
Rear Cover: ISBN
Spine: New spine
+Copyright Page: "TM"; "4th Edition, August, 1979"; Jean Wells credit; +"Distributed to the book trade in the United States by Random House.."; center justified "Inquiries..." lines; ISBN;
Giants: 19-25
+Hydra: +Smaller raised illustration
Vampire: "per round of immersion"
Page 111: No prices;
DMG not listed as "Future Release"
+Page 112: No prices; +No prices next to STAR PROBE; +No prices next to STAR EMPIRES; "send for our catalog."; "potpourri" Gencon ad
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5th
*Front Cover: *Yellow-banner reads "ADVANCED D&D" but no outlined letters; *TM after banner text; Wizard logo; *smooth textured
+Flyleafs: White
*Pages: *rough
*Stitching: *approx 1 1/4", *8 or 9 stitches
Rear Cover: ISBN
Spine: New spine
+Copyright Page: "TM"; "4th Edition, August, 1979"; Jean Wells credit; +"Distributed to the book trade in the United States by Random House.."; center justified "Inquiries..." lines; ISBN;
Giants: 19-25
+Hydra: +Smaller raised illustration
Vampire: "per round of immersion"
*Page 111: *Overhauled catalog
*Page 112: *Overhauled catalog; *"send for our free catalog."; *"potpourri" line removed from Gencon ad
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As you can see, there are sweeping changes between the 3rd Plus and the 4th Alpha. The missing answers to the 4th Gamma will help determine where to draw the line between the 4ths and the 5ths. (Wherever the most change occurs makes sense.) The differences between the 4th Alpha/Beta are fairly minor, only a stitching change, the smaller hydra, and the removal of the price notes for STAR PROBE/STAR EMPIRE.
Good work, everyone, and by all means please keep that info coming and I'll update as required.