There's a lot of overlap between the two, but you can't go wrong with either option, if you love both biology and chemistry.
Biochemistry is more about discovering how life works. Biochemists figure out how different proteins interact with each other, and how those interactions are important in the processes that keep us alive.
Biochemical engineering is more about rearranging these interactions to make life work better. Biochemical engineers often make modified proteins, or devices, which help regulate human health when it's out of balance.
Hope this helps!