First, the two first tools (Trees) of the LTP, namely the Goal Tree (GT) and Current Reality Tree (CRT) are based on facts. The others, Evaporating Cloud (EC), Future Reality Tree (FRT), Prerequisite Tree (PRT) are based on high probability things will happen as planned.
The components of a Goal Tree, called Necessary Conditions (or NCs) are factual needs necessary to achieve the Goal. The Current Reality is described in a CRT in a way that can be checked and proven, based on facts.
As soon as the people are working on the future, from Evaporating Cloud on, it can only be described in probabilities, as things may not exactly turn out as planned. Theory of Constraints’ Logical Thinking Process may need to rely on other tools and methods than Negative Branch Reservation (NBR) to mitigate the risks.
Furthermore, the time to accomplish the necessary tasks is an evaluation at best.
Finally Bill summarizes what Logical Thinking Process is:
a structured way to move from an ill-defined system level problem to a fully implemented solution.