(N/A) $rigid$ $body$ is an idealized object in physics where the distance between any two particles remains constant,regardless of the external forces applied. It does not deform under stress.
$A$ $solid$ $body$ is a state of matter characterized by structural rigidity and resistance to a force applied to the surface. Unlike a $rigid$ $body$,a $solid$ $body$ can undergo deformation (elastic or plastic) when subjected to external forces.
Key differences:
$1$. $Rigid$ $body$ is a theoretical model; $solid$ $body$ is a physical state of matter.
$2$. In a $rigid$ $body$,the relative distance between particles is invariant. In a $solid$ $body$,the relative distance can change due to deformation.
$3$. $Rigid$ $body$ dynamics ignore internal stresses,whereas $solid$ $body$ mechanics (like elasticity) account for them.