Comparing two algorithms

Hello everyone! The problem I am dealing with is that, when I run the same analysis i.e., a combined mechanical load and thermal field, in the first case in the use of a static general step by introducing temperature as a predefined field, while in the second case in the use of a coupled temp-displacement step by introducing temperature as a boundary condition, I get different results. Which one of the two algorithms is correct and how can I check the validity of the results? Thanks in advance!