If you're comparing the initial Mhz figure of 4644MHz vs 4704Mhz? that's not 100 but 60Mhz and if you're comparing the default clock of 3500Mhz vs 4000mhz, that is a 500Mhz difference, this alone tells you it is not the same CPU.
Other differences such as the Overclock record of 8171Mhz vs 8670Mhz tells us it is not the same CPU. If both 8320 and 8350 were the same, both would be capable of achieving the same approximate record.
Where you are correct is that these two CPUs are based on the same platform (Piledriver) but that is no secret, even the Intels have different models of the same platform Sand and Ivy Bridge, Haswell (sockets), those are the platforms and the different number designations are the different models (or improvements) of the same CPU platform.
Edit: The 125Watt TDP on both 8320 and 8350 also proves the 8350 is not an overclocked version of the 8320. If it were, it's TDP would be higher or the 8320's would be lower.