SHUFPS is able to shuffle any of the numbers from one source operand to the lower two destination fields; the upper two destination fields are generated from a shuffle of any of the four SP FP numbers from the second source operand. By using the same register for both sources, SHUFPS can return any combination of the four SP FP numbers from this register.
UNPCKHPS performs an interleaved unpack of the high-order data elements of first and second packed operands,and it ignores the lower half part of the sources.
UNPCKLPS performs an interleaved unpack of the low-order data elements of first and second packed operands,and it ignores the higher half part of the sources.