Why we wana to know the diff of this two term?
Because the output of the device DVD : esp in some Chinese DVD Device, we sometime find that the color diff signal
signed with "YCBCR" and some signed with "YPBPR". What is different?

Y Cb Cr & Y Pb Pr has different H scan freq.
YCbCr is 15k, and YPbPr is 30 k.
in general, the signal above 480P H scan above 30K ,can called that it is YPbPr.

the different of the scan line makes the difference that in system solution route design.
as we know, that in general ,the video dedoder ( Video DeCode -> SAA7114,SAA7118,VPC3230
by using analog processing ) normally can operated the signal up to 15K.

So the signal input above the 30K should using the ADC(ADC -> ADC9883,ADC9884,ADC9888)
 to convert the analog to the digital,and then can pass to the digital video processor.

So,while video device design,the video engineer will makes different route design for the different input signal
types : one for signal bellow the 15k ,and the other above 30k.And so, the engineers of system solution makes
different terminate to indicate that there are two difference for color difference input or output.

that is all we now see : the YCBCR and YPBPR

Definition of: YPbPr

The designation for analog component video signals. The "Y," "Pb" and "Pr" are sets of three inputs or outputs on better video equipment and TVs. The three cables used in a YPbPr connection represent higher quality than the single-wire composite cable commonly used to hook up video equipment, because the brightness and color components of the signal are maintained separately. The YPbPr signals are derived from the red, green and blue (RGB) colors captured by a scanner or digital camera, and RGB is converted into brightness and two color difference signals (B-Y and R-Y) for TV/video. See component video.

YPbPr and YCbCr
YPbPr component video is the analog counterpart of digital component video, which is YCbCr. Whereas YPbPr uses three cables between video equipment, YCbCr uses a single cable. See Y (B-Y) (R-Y), YCbCr, YUV, YUV/RGB conversion formulas and color space.

by Makin 070709 thanks. :)