The following photo shows both 1838 obverses side by side. The first has "Liberty" in raised letters which I believe represents the "Curved Date" variety and the second has "Liberty" incused which represents the "Straight Date".
Click on the thumbnail image for an enlargement.
Besides the difference in the word Liberty, the raised shield lines appear to be broader on the obverse with Libery raised.
The raised Liberty obverse die is known only on original issues including J76B-J76C/P89A-P89B, J79/P89, J82/P90, and J83/P91.
The incused Liberty die is original only on J79A/P86.
It was used for restrikes made in the 1870s on J76-J78/P82-P85 and J80-J81/P87-P88.
Photos used are courtesy of the National Numismatic Collection of the Smithsonian Institution.