ZBR and ZPD: Is there a difference?

The paper considers some problems of understanding the content of the theoretical notion of zone of proximal development in the English-language literature, related to unavailability of sources and some inaccuracies in translations. It is shown that, as a result of such inaccuracies, the notion of zone of proximal development (ZPD) turns out to be different in terms of its theoretical content from the notion of zona blizhayshego razvitiya (ZBR) (зона ближайшего развития, ЗБР), so that we can say that ZPD is not the same as ZBR. Simplification and fragmentation of basic theoretical ideas lead to some serious consequences, which cause difficulties both in the search for a common understanding and further development of cultural-historical theory, as well as in the practical application of ZBR in educational practices.