The second picture is image of White Dzambhala. Blue or turqoise dragon is a figure also in sache (tibetan geomancy or like in chinese feng shui). but more specifically I cant remember. maybe connection with nagas and wealth also.
Quote from Robert Beer, The Handbook of Tibetan Buddhist Symbols:
The azure or turquoise dragon is the vehicle of many Buddhist protective deities, aquatic or storm gods, and guardians of treasure.
The text goes on suggesting that, as a treasure guardian, the Sino-Tibetan dragon may be related to the Indian Naga (with whom it also shares a strong affinity with weather control), just as Gert said above.
When there is no one to provoke anger, how shall we practice patience?