The POPA instruction pops the eight 16-bit general registers. However, the SP value is discarded instead of loaded into the SP register. The POPA instruction reverses a previous PUSHA instruction, restoring the general registers to their values before the PUSHA instruction was run. The first register popped is the DI register.
The POPAD instruction pops the eight 32-bit general registers. The ESP value is discarded instead of loaded into the ESP register. The POPAD instruction reverses the previous PUSHAD instruction, restoring the general registers to their values before the PUSHAD instruction was run. The first register popped is the EDI register.