The violin and the cello both have four strings. However, the strings are tuned to different pitches. The lowest string on the violin is tuned to a G, while the lowest string on a cello is tuned to a C an octave plus a fifth lower than the G. The remaining strings move by fifths on both instruments. This gives the pitches C, G, D and A on the cello and G, D, A and E on the violin.
The thickness of violin and cello strings is significantly different. You would not be able to take a violin string and put it on a cello. In general, the lowest strings on a cello and violin will be the thickest strings, and the strings become thinner as you ascend. A low C cello string is almost twice as thick as the lowest G string on the violin. Additionally, some performers purposely select thicker than average strings to get a richer tone.
The difference in tone between a violin and cello string is distinct. The cello strings have a darker, fuller sound, while the violin strings have a brighter, more penetrating sound. The lowest strings on both instruments produce the most gritty sound. The second strings are generally used for lyrical singing passages. The third string on both instruments has a penetrating but full sound, and the highest strings are narrow-sounding and penetrating. As you go higher, the strings become thinner, creating a more brilliant sound in the higher registers. The main difference is that the cello will always have a darker and deeper sound than the violin, due to its lower register.
Cello and violin strings have significant differences in length. A cello string is just over two times longer than a violin string. The violin strings must stretch approximately 32.5 centimeters from bottom to top. Violin string length has been standardized to within a small variation of 32.5 to 32.8 centimeters, while cello string lengths vary considerably and fall approximately in the range of 68 to 70 centimeters. There are some cellos that even use strings as long as 72 centimeters.