Why is the data received from Yandex.Metrica obtained via the API and in the service itself different?

Question

API

The data received via the API is different from what is seen on the service itself. The difference in percent is 10-20 in different directions.
Let's say a request for the tech_devices preset (by device type) returns that 1314 came from the PC, and in the service report for the same period 1234
What's the problem?

Answer 1

Most likely you have additional filters/conditions set in the service settings.