Let’s look at the leaves. Here are the leaves of the first plant. . .
So let’s look more closely at the inflorescence. The first plant. . .
Okay, let’s put each plant’s flower side-by-side. How would you describe the difference?
For the plant on the left, the flower’s spurs rise upward, spread apart a bit, and extend above the point of connection to the flower stalk. For the plant on the right, the flower’s spurs are shorter, rounded, and barely above the connection point to the flower stalk.
The left-most flower is from a Dutchman’s breeches (Dicentra cucullaria) while the right-most flower is from a Squirrel corn (Dicentra canadensis).
You might find these plants when their flowers are dying or when they’ve already developed seed capsules.
Or you might find only the foliage. The next comparison image shows leaves which look a bit different. It seems like the Dutchman’s breeches leaves are somewhat wider within their dissected lobes — at least with these specimens. This may be misleading since illustrations (and comments) in field guides show (and state) the leaves are mostly the same.
The best way to distinguish between these two Dicentras is to find them in bloom.