They're within an order of magnitude of each other but they're not _in_ the same order of magnitude. 2 would be in the 0th order and 6 would be in the 1st.
But even if it weren't so, I'm not sure what your point is. Do you have a reason for thinking that orders of magnitude is a good way to compare alcohol consumption?
But even if it weren't so, I'm not sure what your point is. Do you have a reason for thinking that orders of magnitude is a good way to compare alcohol consumption?