https://community.arm.com/thread/3104

TCMs are connected directly to the processor, not through the bus.  So you don't have bus arbitration or the overhead of the bus protocol when you speak to them. IRAM is an Internal RAM. In most of the SOC, we usually have IRAM of size 128KB or 64KB etc... This is usually termed little faster than the SRAM access.
So need to know how this IRAM is different from TCM memory interms of connection and access. System on Chip，縮寫：SoC
So TCMs are memories connected directly to the processor.  They also typically (but not always) fast - that is the same or near processor frequency,
IRAMs in your case are just means on SoC memory.  It'll still be connected through the bus.  In terms of speed, typically much quicker than the bulk off-chip memories.  But probably still lower frequency than the processor itself.  As the bus usually runs at a lower frequency than the processor.
IRAM vs TCM
The main difference between them then is how the connect to the processor.  TCMs directly to the processor, and IRAMs through the bus interface.  What benefit this gives is system specific.  Typically its going to be that with TCMs there can be contention with other masters.