As he ramps up his presidential campaign, Mr. Biden appears to have taken some lessons from Mrs. Clinton’s defeat — but paid no heed to others. Even as he structures his campaign around an implicit critique of her general election effort, offering a full-throated appeal to working-class voters at his opening event in a Pittsburgh union hall, Mr. Biden has embraced the kind of incumbent-like, establishment campaign that left Mrs. Clinton open to a fierce primary challenge from Senator Bernie Sanders.

Like her, he touts his decades of government experience, intimate knowledge of world leaders and close relationship with former President Barack Obama.

But unlike Mrs. Clinton, who faced attacks from just one opponent, Mr. Biden is running against a historically large and diverse field of candidates, some of whom have already spent months scrutinizing parts of his long political record…

His gender may also help Mr. Biden appear more relatable than Mrs. Clinton: Research has found that it is much harder for female candidates to be rated as “likable” than male candidates — and that they are disproportionately punished for traits like ambition that voters accept in male politicians.