Why do Democrats always seem to march in Lock-step

Both political party soldiers for the most part take their marching orders from the top.  But for some reason it is the Democrats who seem to march in lock-step more than their counterparts.   One need only look at the recent votes in the U.S. Senate, where the Democrats really goose-stepped their way through the Trump cabinet confirmation votes.  And of course it is Democrats who call Republicans Nazis.  But then perhaps there  is a simple explanation for the glaring difference between the two parties.  Most Republicans come from the rural parts of the country where they are more likely to depend on themselves---in other words many are individualist.  Whereas those across the aisle tend to come from the huge metropolitan centers where collectivism is the norm and individualism the exception.  It is the Democrats who goose-step while the Republicans march to a different drummer!     aaaaaaaaaaaaaaaaaaa