What are the differences between NUMA architecture and SMP architecture?

NUMA Architecture: Non-Uniform Memory Access architecture.
SMP: Symmetric Multiprocessing architecture.

In a Symmetric Multiprocessor, the architectural “distance” to any memory location is the same for all processors, i.e. “symmetric”.

In a NonUniform Memory Access machine, each processor is “closer” to some memory locations than others; i.e. memory is partitioned among them Asymmetrically.

From my understanding, most of current architectures are SMP+UNMA if we consider cache is also part of memory hierarchy.

Part of above answers are copied from https://www.quora.com/What-is-the-difference-between-SMP-and-NUMA-architectures