SUMMARY
The Hong Kong figure is what we would consider the Mattel standard, on which all Clawfuls are based. Characteristics include bright red colors (head claw, armor, and shorts), mid-dark blue shorts and boots, both Skeletor style or buzz-off style leg molds, and sharp, well-defined face paint. Heads are usually soft but can be found semi-hard or hard, sometimes even oversized.
The Hong Kong figure can be marked © Mattel Inc. 1981 HONG KONG, or it can be marked © Mattel Inc. 1981 (without the HONG KONG) text. Both the Skeletor legs and Buzz-Off legs variants can come in both stamp configurations.
The armor, just like the figure can be marked with or without the HONG KONG marking on the back half. The chest stripes on the armor can vary considerably from one to the next, from very dark browns to lighter browns, from short, thick stripes to much longer stripes.
Lastly, while we consider this a Hong Kong figure, it was also produced for some time in China. This is most likely why we see some figures marked Hong Kong and others just marked © Mattel Inc. 1981, as well as why we see quite a range of variance in the heads, chest paint, and COO stamps.