Question

what is difrent between cp and cv

Answer 1

cp is constant pressure
cv is constant volume

Answer 2

Both C's are specific heats. Cp is the specific hear at constant pressure and Cv is the specific heat at cosnatnt volume. (The C is usually capitalized and the p or v is usually a subscript).

For an ideal gas, Cp = Cv + R,
where R is the ideal gas constant, 1.986 calories per mole per degree C.