A head to head comparison of the New Jersey 2020 Primary gives us an idea of the breakdown of voters.
Joe Biden received 805,742 (60%) votes to beat Donald Trump, who received 398,628 (30%) votes and Bernie Sanders, who received 137,921 (10%) votes.
In the Primary, Biden won 16 counties in the 3-way match up. Trump trailed behind Biden winning 5 counties with Sanders winning nothing in New Jersey Primary.
Bernie Sanders vs Joe Biden
Joe Biden vs Donald Trump
Donald Trump vs Joe Biden
In a head to head match up on just the total number of votes, Hillary Clinton (63%) beats Bernie Sanders (37%). Hillary Clinton (61%) beats Donald Trump (39%). Donald Trump (52%) beats Bernie Sanders (48%).
These 10 counties play an important role in these primary elections. Even if a candidate can get a sizable majority in the larger counties (Bergen, Essex and Ocean), it is possible for the other candidates to catch up from the smaller counties.
Biden's win at Bergen and Essex (the two largest counties) gave him a huge vote advantage over both Trump and Sanders. Even though Trump won the county of Ocean by a noticeable margin, Biden's steady win at most counties gave him the upper hand in the State of New Jersey.