First, there is a big difference between guzheng and guqin in appearance. The guqin is much smaller than the guzheng, and the whole body is more compact and exquisite. On TV, you can often see the ancients walking around with the guqin, but the guzheng is not easy to operate because of its large size. The guzheng is almost twice as big as the guqin. Moreover, the guqin has seven strings, and the number of strings is much less than that of the guzheng. The current guzheng has 21 strings, and the number of strings of the guzheng is only one-third of that of the guzheng. Therefore, in terms of appearance, it is actually easy to distinguish the guqin from the guzheng. The one with more strings is the guzheng, and the smaller one is the guzheng.
Secondly, the sound ranges of Guqin and Guzheng are different. Although the guqin only has seven strings, one string of the guqin can produce multiple sounds, spanning multiple ranges. The pronunciation of the guqin is not affected by the number of strings. One string can span four octaves. This Similar to Pipa. Although Qi Pa has only four strings, one string can produce multiple sounds, covering a wide range of sounds. The guzheng has many strings, basically one string produces two sounds.
Third, the timbre is different. This is the biggest difference between the two. If you want to distinguish the guqin and the guzheng in a piece of music, the most important thing is to listen to their timbres. The expressive power of guzheng will be stronger, because the speaker of guzheng is larger, the pronunciation is more powerful and rich, and the style is relatively changeable. However, the sound box used by the Guqin is relatively small. Compared with the Guzheng, the sound it produces is not as powerful as the Guzheng. The overall feeling is relatively simple, without too many gorgeous modifications. Guzheng can have more fingering changes, and it sounds richer than Guqin. I think this is one of the reasons why more people are learning Guzheng and fewer people are learning Guqin now.
In addition to these three differences, their histories are also different. Guqin has a longer history. The playing techniques of the two instruments are also different. Compared with Guqin, Guzheng is more complicated. Sometimes both the left and right hands need to be plucked, but Guqin basically requires the left hand to press the strings and the right hand to pluck.