On the reference page for
SurfaceFormat, it indicates that the Bgra4444 format is an unsigned format which is 16-bits long, with 4 bits per color with alpha. Further down the page, it describes the Rgba64 format as being 64-bits long, with 16 bits per color (including alpha).
Why does one format list R-G-B as the color order, while the other lists it as B-G-R? I understand it likely has to do with the underlying hardware, but there certainly needs to be a reason that it wants it in a reversed order for the other format.