What is the different between save(), create() and update () in django rest framework?

I m confused when making api on django rest framework using serializers, please tell me exact different between save(), create() and update() methods, my code sample is as follow,

View.py

class AddUser(views.APIView):
    serializer_class = UserForAdminSerializer

    def post(self, request, *args, **kwargs):

        serializer = UserForAdminSerializer(data=request.data)

        if serializer.is_valid():

            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

serializers.py

class UserForAdminSerializer(serializers.ModelSerializer):

    first_name = serializers.CharField(max_length=30)
    last_name = serializers.CharField(max_length=30)
    name = serializers.CharField(max_length=30)
    password = serializers.CharField(max_length=20, style={'input_type': 'password'})

    class Meta:
        model = User
        fields = ('id', 'url', 'first_name', 'last_name', 'name', 'username', 'email', 'password',
                  'total_exp_year', 'total_exp_month', 'voteup_count', 'is_featured',
                  'is_active', 'headline', 'description', 'profile_picture', )

    def create(self, validated_data):
        password = validated_data.pop('password', None)
        instance = self.Meta.model(**validated_data)
        if password is not None:
            instance.set_password(password)
        instance.save()
        return instance

on the above code in view.py file i m used save() method and serializers.py using save() or update() method so please explain me how it's working and clear my confusion between save() and create()