M23 core is an improvement of M0+ core, for official comparison se here.
Below there is a quick comparison.
Key features of the Arm® Cortex®-M23 core (form ARM web page)
- Cortex-M23 is an implementation of the ARMv8-M architecture. Full details here.
- Using the same debug interface as the other Cortex-M processors.
- Offering the optional micro trace buffer, wake up interrupt controller and fast I/O bus as the Cortex-M0+
- Using the AHB5 specification for the system and memory interface to extend security to the whole system
- Using the latest version of the memory protection specification to simply the setup of regions
- Extends the number of maximum interrupts to 240
- An optional embedded trace macro cell to expand the trace functionality
- Updated debug components that enhance debug operations and simplify usage
- Exclusive memory access instructions to simplify multi-core designs
- Instructions for divide operations to boost performance
- Stack limit checking in hardware when security is implemented
- TrustZone for software and hardware isolation