Help me please to figure out what the difference between value set of device-type and device-property-type
The description of these value sets according to FHIR the same, while the purpose of has a different logic.
As I got it, the Device Property Type could have certain characteristics of the device instance and this value set is defined by implementer. If not, please give me some more information about that particular element.

Thanks in advance!

The device property type value set isn’t ideal and might be outright wrong. (Feel free to raise a change request.) Device properties are to convey aspects of a device such as cuff size, diameter, settings, etc.