请教,这2个warning有什么区别?

请问各位:这2个warning有什么区别?谢谢!

1:***WARNING: NODES 4001 AND 101 IN THE TIE MPC ARE NOT COINCIDENT. THE MPC
WILL CONSTRAIN ROTATIONAL RIGID-BODY MOTION BETWEEN THE NODES.
INTERPRET RESULTS WITH CAUTION OR CONSIDER SUBSTITUTING A BEAM OR
LINK MPC.

2:***WARNING: AN MPC OF TYPE TIE RELATES AT LEAST TWO NODES WHICH, DUE TO
ELEMENT REMOVAL, HAVE NO STIFFNESS IN STEP 1. THIS MPC WILL NOT BE
ACTIVE DURING THIS STEP OF THE ANALYSIS. (THE DEPENDENT NODE IS
21000025, AND TWO NODES WITH NO STIFFNESS ARE 21000025 AND
20000025.)