Do you think that this child is underdevelpoed?

he is 2 and a half, still wears a diaper, uses a binky, can hardley say 2 words at a time, still drinks from a bottle for most of his meals, gets treated litteraly like a baby from everyone in his family, sleeps in his parents bed, always has every single night of his live. I think he is definently underdeveloped. He is also a spoiled brat. and he cried to get his way and his parents give in. A nother little boy i know is 2 and a half and you can have a full conversation with him, sleeps alone, eats realy food by himself and is fully potty trained, not even pull ups