Almost Identical
Sharps Model 1859 / Sharps & Hankins Navy Bayonets
Both of the listed bayonets appear to be identical in construction and fully interchangeable. Both have Collins Type 1 long hilts, an inside muzzle ring diameter of ~20.8 millimeters and a guide slot of ~25.5 millimeters. The only difference is found with the way they are serial numbered.
What makes them different
The Sharps bayonet usually has a small font 5 digit serial number stamped horizontally on the hilt flat.
The example listed below as a Sharps Model 1859 is believed to be correct but it is not serial numbered at all.
Sharps M1859
The Sharps & Hankins Navy Bayonet has a 1 to 3 digit serial number stamped horizontally on the hilt flat in a font ranging from 1.5 to 3 millimeters.
Sharps & Hankins
Speculation and questions
Sharps bayonets without a serial# are known to exist but the example listed here may well be an unnumbered Sharps & Hankins. Without a serial # it is impossible to tell.