Logical Modeling

Logical modelling to model the "AS IS", it defines the context in the Business Architecture. It is the motivation component (Drivers, Goals, Objectives) you see I leave the measures out. And the organization component (organization location actor and role) within the Business Architecture if you like.

Physical Modeling

Physical modeling, is more toward the design and the functionality, it defines the quantifiers, these are also captured at the Business Architecture (Motivation --> measures) and Function. It provides the boundaries in which the solution must work, and as such is hinting towards the Information systems architecture and technology architecture. (I do not believe it is restricted to those).

So when to use what?

Logical as part of your discovery phase, getting approval and understanding of the business, and reaching into the envision.

Physical, more from envision into design, bringing it from "paper" into reality. I do not believe that the physical modeling is limited to objects, it is broader than that....... it defines the limitation, constraints if you like of the system.

System in this context is the collaboration between people, computers and business processes.