FX-4300 FX-6300 FX-8320 Speed Differences

I'm curious about why there's the AMD FX-8320 Vishera with an Eight-Core
running 3.5 GHZ ($180), while there's also the AMD FX-4300 Vishera with a
Quad-Core running 3.8 GHz. Why is the Quad-Core rated at a higher clock
speed than the more expensive Eight-Core, not to mention the Six-Core
FX-6300, which is also rated at 3.5 GHz?

The FX-8320 might be more than I want to spend, but I could get the
FX-6300; it's only $10 more than the FX-4300 on newegg.com. ...though the
FX-4300 was only about $79 or $89 a couple of weeks ago. I need choose
something soon before it goes up in price again.

Is a Six-Core at 3.5 GHz going to be faster, overall, than a Quad-Core
running 3.8 GHz?

Damaeus