Memory type for MacBook 5,1

I have a MacBook 5,1 with aluminum case.

It is NOT a MacBook Pro.

So I guess it is the late 2008 model but I am not 100% sure.

When I look up the model on Apple website, it says the aluminum MacBook takes 667MHz DDR2 memory.

However, when I look at "About this Mac" on my machine, it says currently it has 1067MHz DDR3 memory.

The bus speed is 1.07GHz.

I have never upgraded memory on this machine, so the 2GB memory is originally from Apple.

Did Apple sold me a machine with faster memory than the original spec?

I plan to increase the memory size, but now I am totally confused.

If I follow the recommendation on Apple website, I would be buying a slower memory than what it already on the machine.

The website also says it can only take 4GB while other website says it can takes up to 8GB.

So if Apple could be wrong about my memory speed, should I stick with their 4GB max memory upgrade too?

Can someone tell me why my machine does not match what Apple website describes?

Could I have mis-identified my machine?

Hardware Overview:

Model Name: MacBook

Model Identifier: MacBook5,1

Processor Name: Intel Core 2 Duo

Processor Speed: 2 GHz

Number Of Processors: 1

Total Number Of Cores: 2

L2 Cache: 3 MB

Memory: 2 GB

Bus Speed: 1.07 GHz

Boot ROM Version: MB51.007D.B03

SMC Version (system): 1.40f2

Serial Number: <withheld for privacy reasons>

Memory Slots:

ECC: Disabled

BANK 0/DIMM0:

Size: 1 GB

Type: DDR3

Speed: 1067 MHz

Status: OK

Manufacturer: 0x80AD

Part Number: 0x484D54313132533641465236432D47372020

Serial Number: 0x20320000

BANK 0/DIMM1:

Size: 1 GB

Type: DDR3

Speed: 1067 MHz

Status: OK

Manufacturer: 0x80AD

Part Number: 0x484D54313132533641465236432D47372020

Serial Number: 0x30280000