var array1 = [ {“Num”: "A " },{“Num”: “B” }];

var array2 = [ {"Num": "A ","Name": "t1 " }, {"Num": "B","Name": "t2"}, {"Num": "C " ,"Name": "t3 "}];

var result = [];

for(var i = 0; i < array2.length; i++){

    var obj = array2[i];

    var num = obj.Num;

    var isExist = false;

    for(var j = 0; j < array1.length; j++){

        var aj = array1[j];

        var n = aj.Num;

        if(n == num){

            isExist = true;

            break;

        }

    }

    if(!isExist){

        result.push(obj);

    }

}

console.log(result);