Intel and AMD = different CPU companies
Centrino = type of mobile CPU made by Intel
Atom = looks like an Intel-based 'niche chip', meaning for use only in specific devices (actually had to Wiki that one...

)
Now, as far as Dual Core and Core2Duo go, it's like this... A Dual Core (DC) processor is any CPU with 2 cores, regardless or Brand or Architecture. A Core2Duo (C2D) is a specific type of DC processor. A CPU's 'architecture' refers to the type of technology and instruction-set it contains. The 'Core2' architecture was introduced a few years back, and shortly after, Intel started making them DC, hence the 'Core2Duo' brand name.
All Core2Duo's are dual-core CPU's, but not all dual-core CPU's are Core2Duo's.
As far as the best CPU of those listed, the C2D will utterly smoke everything else in terms of performance.