I differentiate by location/habitat, body shape, flight characteristics, sound upon flush, and distance they flush at. Color is also a possibility but a silhouetted bird is mostly black. The first three above are my major cues as they are so different. I have seen snipe while hunting woodcock but it was rare and it was an obvious snipe area tucked into the woods rather than the snipe in woodcock habitat. The only time I have seen woodcock in snipe habitat has been at night and that was mostly in the spring.
Woodcock and snipe appear similar in books, in real life they are as different as quail and woodcock. I have much more concern distinguishing snipe from a number of other shorebirds- none of which are legal game and share the same habitat. It isn't tough but it can be tricky at times. If I don't positively know, I don't shoot.
Last edited by woodmaster81; 10/14/19.