The term "digital quality" is ambiguous. Digital quality (quality of digital signals) can be worse than that of analogue quality. In real life, we have analogue signals. When the analog signal is digitized, it loses information. The higher the number of quantization levels, the higher the resolution, but it will always be less than the resolution of the original analog signal. Digital signals have the advantage that these can be processed and stored easily. There is no loss of information during transmission of information.

From the point of view of learning English, you need to know that transmission may be done by digital or analogue means. Now you can search the internet for the science and meanings of these words. Do some work yourself.