Copy and paste operations keep the same object size (in drawing units).
Using the INSERT or ATTACH command will also scale the inserted command using the specified units for the two drawings, as long as the “Scale objects from other drawings upon insert” setting is on (-DWGUNITS command).
Using the INSERT or ATTACH command will also scale the inserted command using the specified units for the two drawings, as long as the “Scale objects from other drawings upon insert” setting is on (-DWGUNITS command).
Source: Autodesk
