When comparing lenses, the model of the lens provides indicators on the differences between them. Between the 50mm f/1.8G and the 50mm f/1.4G, the difference between them is the aperture. The aperture is indicated by the number after the f/ in the model. Aperture is one of the most important aspects of a lens because it determines how much light is allowed in the lens. The more light allowed in, the better low light performance the lens has—the lower the aperture, the more light that is allowed in. Between the two, 1.4 is lower than 1.8, which means the 1.4 lenses will have better low light performance.
The critical difference between the Nikon 50mm 1.4 and 1.8 f stops to their point on the scale. The f1.4 and f1.8 stops are not a complete stop apart but, rather, only two thirds. This partial stop means that they are not too different and commonplace. It would be challenging to get different results with both lenses.
This result is because f1.4 can possess a larger aperture; it may allow lighter and accomplish improved exposure in a shorter period. This quick time means it can capture photographs faster than the f1.8 lens.
This quicker exposure should diminish the occurrence of blurring in case of the subject moving swiftly, as well as shoot additional photos within a given time frame. The f1.4 is also able to create sharper images than the f1.8 lens. Once you go higher, you will suffer the loss of any benefit of the sharpness that the lens provides.