The black one is the original and hasfixed timing, it should be timed at 20-22 degrees BTDC. The one with thenickle plated ABS case is the newer version (not the latest version) and it has an auto advance feature, it should be timed at 28-30 degrees BTDC. Both of them will work but neither has proven to be all that reliable or robust, both are genuine CRRC Proreplacement parts.

w8ye is right, the much better choice would be an ignition from Rcexl timed at 28 degrees BTDC.