Pack, crowd, cram, stuff, ram, tamp are comparable when they mean to fill tightly or cause to fill tightly something which holds a limited amount or presents a limited space.
Pack, in its basic sense, implies a forming into packs or bundles for convenience in storing or transporting. Additionally it may imply close, orderly arrangement in receptacles of determined size, and, as a corollary, compact and complete filling. In extended use it may suggest completeness of filling or, frequently, an excessive or uncomfortable filling, without any relation to the ideas of storing or transporting.
Crowd (see also PRESS ) implies the presence of great numbers of persons or things in proportion to the space, area, or time; the term often suggests numbers so great as to press upon or otherwise seriously inconvenience.
Cram carries a similar implication of pressing so as to bruise or squeeze, but the word usually also suggests a forcible and, sometimes, disorderly insertion into a receptacle or space of more than it can easily or comfortably or safely take.
Stuff implies the use of such a material as padding, wadding, or straw in expanding or distending. From this specific meaning comes the more general meaning of to fill so that a thing bulges or so that the filling protrudes.
Ram nearly always retains some notion of its basic implication of pounding and tamping, but this implication is sometimes obscured or subordinated and that of stuffing or cramming as if by pounding in is stressed.
Tamp, which often comes close to ram in meaning, originally meant and still means to plug up a drill hole above a blasting charge with clay, earth, or similar material. In its extended use it implies a series of blows which press something into a confined space or under, over, or about another thing that needs to be supported.