similar to a Dark Brown Leghorn but in a quick comparison of the Standard descriptions there are some slight differences. For instance, in the description of the BACK in the females:
Brown Cochin: Dark Brown, densely stippled with black of sufficient lustre to present an overall effect soft and vivid; yet free from dullness on the one hand, and not having enough sheen or lstre to transcend the general tone of rich, dark brown; free from shafting.
Dark Brown Leghorn: Web of feathers on surface, black, moderately fine stippling with rich reddish brown, the brown to predominate; free from shafting, purple, and regular penciling; exposed portion of feather to carry a lustrous green sheen; unexposed portion of feather, dull slaty black.
Breast coloration is slightly different as well. Breast of the Cochin female is listed as "Light brown, stippled with black," in the female where the Dark Brown Leghorn female breast is described as "Same color as described for back, except that breast carries slightly lighter shade...."