I'm a big fan of the Kennedy half and recently picked up an accented hair variety. These appeared in 1964 in proof only. An early obverse die was used with some slightly different characteristics including accented hair (also a different reverse die was used but that was apparently used with accented and normal obverse dies). Here is my accented hair Kennedy and a normal proof.



Some diagnostics.....

The truncated serif on the 'I'


The 'broken' rays.


And, of course, the accented hair.


There is also a difference in the FG initials, but I'm too lazy to photograph them (I really need to upgrade my cam).

In hand it is really easy to tell the difference - can you see it from these pics? The authority on this variety online is here -> LINK - definitely worth a read!