The compare view allows the joined view of two (or more) annotated documents. As of version 1.3, it only allows comparison of the spans of the annotation mentions.
The compare view shows the document in text view, and the annotated mentions underlined. Colors, however, do not signal different entities, as in the regular annotation view. Instead, each annotator is represented by a color, and all annotations that are not in agreement are underlined by the annotators color. Annotated spans that are marked by all annotators are underlined in gray.
The panel on the right shows some numbers about the agreement. Note that this is only a rough estimate, and only shows observed agreement.