why do i get different results in laravel query builder?

In your first query, there is no “where” clause.

In query builder…

->leftJoin('detail_data as detail_B', function ($join) {
    $join->on('detail_A.id_jenisdata', '=', 'detail_B.id_jenisdata')
        ->where('detail_A.tahun','2018')
        ->where('detail_B.tahun','2019');
})