Bodhisattva Maitreya is sometimes represented as a buddha because, according to the scriptures, he is the next historical buddha to be.
Unlike other buddhas, he often sits in the European way. Besides, he can be identified through his symbolical gesture known as dharmachakra mudra.
The stupa at the top of the arch behind him is one of his attributes. He is flanked by two attendants.
Another common attribute is the ritual water pot on the lotus next to his right arm.
Even when he sits in the lotus position, his hand gesture and the pot of water on top of the lotus (next to his left arm, this time) enable us to identify him beyond doubt.
In this case, we can identify him thanks to the stupa in his headdress, along with the hand gesture.