SIMD and vector instructions

There is some confusion between the terms SIMD and vector. Clearly, SIMD instructions work on vectors made up of elements that can be 8-bit, 16-bit or 32-bit integers, single-precision or double-precision floats. Similarly, compiler developers for instruction sets with SIMD extension talk about the possibility of "vectorizing" scalar code, i.e. using SIMD instructions. However, when it comes to defining the instruction types of an instruction set, there is a clear difference between SIMD instructions and vector instructions: to perform the same operations, there are many more SIMD instructions than vector operations in the instruction set.