I get what you're saying - some of the differences are subtle. Can you post pics? There are folks who raise CP on here (like @JanetMarie) that may be able to help you identify if you do have CP.
With regard to gander color, there are apparently some lines that have more color (gray markings)...
The Livestock Conservancy has a detailed article that may help. Some of the differences are subtle, but the single lobe in the CP is one.
Congrats on your new geese!