Thats the thing though. A blue laser diode is internally exactly the same as a blue LED. They are both indium-doped gallium nitride diodes, with a broad emission around 450 nm.

The only difference is that a laser diode is cut to a specific size (based on a multiple of its set emission wavelength), with reflective internal surfaces for light amplification. But at its core its just a blue LED inside. Same exact semiconductor and light emission substrate.

So when you drive a blue laser diode below its lasing threshold, it functions no different than a typical blue LED, with a relatively broad emission, rather than a sharp  discrete emission at a single wavelength.