The object manager is the one that copies GROUPS of OBJECTS with all the attributes that are associated with it. The project merge is used for COPYING the entire project ALONG with all the objects. This is why it does not have to CHECK for the attribute constraints before copying. The Object manager however has to make sure of the object attribute matches before copying the objects. The object manager cannot be run from the command prompt directly whilst the project merge can be run directly

The object manager is the one that copies groups of objects with all the attributes that are associated with it. The project merge is used for copying the entire project along with all the objects. This is why it does not have to check for the attribute constraints before copying. The Object manager however has to make sure of the object attribute matches before copying the objects. The object manager cannot be run from the command prompt directly whilst the project merge can be run directly