We got a link to a nice site that compares what is so different about this new AMD BE processors.
Just as Dual core 4000+, BE-2350 works at 2,100 MHz and it is a G1 stepping but it needs only 1.25W. 4000+ works with 1.25 to 1.35V. They are both made in 65 SOI marchitecture have 2x128 KB cache and 2x512KB of L2 cache and support socket AM2.
Thermal design power for 4000+ and 3600+ clocked at 1,900 MHz is 65W while BE-2350 and BE-2300 have TDP locked at 45W.
To cut the long story short, these CPUs are pretty much the same but the BE will run cooler and will probably overclock well.
You can see the rest of the specs here.