In an orchestra, the string section is a broad category that includes various string instruments such as the violin, viola, cello, and double bass. Each of these instruments has its own section within the string section.
The cello section, therefore, is a subsection of the string section. It consists of the cellists in the orchestra who play the cello, which is a large, four-stringed instrument that is held between the legs while being played. The cello section typically plays an important role in the overall sound and harmony of the orchestra, providing rich and deep tones to the music.