Question

differences between machine operation and pseudo operation

Answer 1

The most common type is a pseudo-op for the sequence of instructions needed to get a 32-bit constant (e.g. an address) into a register. Since a fixed-with 32-bit instruction doesn't have room for an arbitrary 32-bit immediate, the machine can't do it in one instruction. However, there's usually nothing to gain from separating the pair of instructions with 16-bit immediates, it would be annoying to do it manually. (IIRC, some superscalar in-order CPUs recognize such pairs when executed back-to-back, still running them in parallel even though they modify the same register.) ARM assembler pseudo-instructions MOV32 and ADRL do this.