The official Cortex-R page lists three main items: - Fast, bounded and deterministic interrupt response - Tightly Coupled Memories (TCM) local to the p

The official Cortex-R page lists three main items: - Fast, bounded and deterministic interrupt response - Tightly Coupled Memories (TCM) local to the processor for fast-responding code/data - Low-Latency Interrupt Mode (LLIM) to accelerate interrupt entry I haven't cross-compared the relevant features to the Cortex-M cores, but the M cores are certainly more common and definitely perform well too.