By definition, superscript or subscript is a character, which can be a number, letter, or symbol, placed above or below the type line.
Superscripts appear above the normal line of type. They’re commonly used to symbolize exponents, footnotes, ordinal indicators, and trademarks.
Subscripts are placed below the baseline. They’re usually used in chemistry to illustrate the molecular structure of chemical compounds such as water (H20).