Theory of change
A theory of change explains how a program will achieve its ultimate goal. It illustrates the web of factors influencing the program and the goal, including things that are out of your control. A theory of change gets at the big picture: what you want to do, how you will get there, what assumptions are being made, and the social context it is all happening within.
On the other hand, a logic model is a simpler, linear chain of cause and effect showing how a particular program will achieve its intended effect.
See also: program theory