Clearly, PLEX have more to offer, which is why EVE Online is phasing out EVE time codes in favor of PLEX activation codes. The net prices are identical, but the effect is that subscription time will be awarded as PLEX, which you can use in all of the many ways you already use PLEX. For more details and a quick rundown of how PLEX work, check out the official blog entry.
In other EVE news, CCP has released to its YouTube channel a Recording History video chronicling the events that triggered the Bloodbath of B-R5RB. We've included it below. [With thanks to tipster J!]