complement vs reverse complement
Each nucleotide in a double stranded DNA molecule is paired with its Watson-Crick counterpart. This counterpart is called its complementary nucleotide.
Double stranded DNA sequences are represented by the upper (sense) strand sequence going in the direction from its 5′- to 3′-end.
The complementary sequence is thus the sequence of the lower (antisense) strand in the same direction as the upper strand.
The reverse sequence is the sequence of the upper strand in the direction from its 3′- to its 5′-end.
The reverse complement sequence is the sequence of the lower strand in the direction of its 5′- to its 3′-end.