Word may well copy to the clipboard in multiple formats, perhaps generic system defined formats and private formats only Word implements. The RichTextBox can probably only accept a few formats such as text, RTF text, and a set of object formats such as an OLE bitmap, WMF, EMF, etc. that the system will synthesize.

Your "high fidelity" snippet probably isn't something that RichEdit can accept without distortion.

See Clipboard Formats