I'm learning X86 assembly, when I learn SSE and AVX instructions, I found that there are several instructions which don't share the same opcode but have the same effect. For example:
all of MOVAPS, MOVAPD and MOVDQA move 128/256 bits aligned data from/to xmm/ymm.
all of PAND, ANDPS and ANDPD and the same with other bitwise operations do bitwise operations on each bit.
I have checked intel manual but I can't tell the difference. What are the differences among them if they are different? or Why don't they share the same opcode if they are the same?