The x86 simulator and AI Engine simulator have some important differences when it comes to packet switching and run-time parameters (RTP). See Run-Time Parameter Specification and Explicit Packet Switching in AI Engine Kernel and Graph Programming Guide (UG1079), if you are not already familiar with these constructs.
Both packet switching and RTPs exhibit behavior that can manifest itself as a difference between the AI Engine simulator and the x86 simulator. It is important to understand that this dissimilarity is still correct in both cases. As discussed in Explicit Packet Switching in AI Engine Kernel and Graph Programming Guide (UG1079), packet switched streams are non-deterministic in all design flows (x86 simulator, AI Engine simulator, and hardware emulation) but the computational order is still deterministic.