According to the Cornell Laboratory of Ornithology:
"The Wilson's Snipe was recently recognized as a different species from the Common Snipe of Eurasia. The two snipes look extremely similar, but differ in the shape, patterning, and usually the number of the tail feathers. The Wilson's Snipe typically has 16 tail feathers, whereas the Common Snipe has 14. These numbers vary, however, and a Common Snipe may have from 12 to 18 tail feathers.
There is so much to learn about nature that we can never hope to satisfy our quest for knowledge.