I feel that SIMD vs vector is not the most useful distinction to make. Yes, at the ISA and binutils level there is a difference in terms of number of instructions and ugly encodings. But the actual application source code can actually look the same for SIMD and vector - vector-length agnostic style is helpful for both.

Instead, it seems more interesting to focus on preparing more applications for either SIMD or vector: with data-parallel algorithms, avoiding branches etc.