You are giving too much attention to the names of APIs without understanding the technology behind them.
Mantle - the API that defines how every library works is in every API. Metal, DirectX 12, Vulkan, they all were given birth thanks to Mantle. Thats most important thing. Of course everyone of them is different in some ways. But at the core they are pretty much the same, thanks to what - coding will be fast and easy.
Mantle - the API that defines how every library works is in every API. Metal, DirectX 12, Vulkan, they all were given birth thanks to Mantle. Thats most important thing. Of course everyone of them is different in some ways. But at the core they are pretty much the same, thanks to what - coding will be fast and easy.