The difference between chop and grind is that grind reduces the food to much finer particles and can even mean grinding the food into a powder or paste like consistency.
Chop or chopping is the cutting of food into smaller and bite sized pieces.
An example of grinding would be grinding of coffee beans into coffee grounds which can also be done to other foods as well.
Grinding basically reduces the food to very fine particles or even a paste like consistency, by using friction or a grinder.
Grinding of foods is often used to create a uniform texture and to release flavors or even prepare ingredients for certain recipes such as grinding of meat, coffee beans spices etc.
Food processors, grinders such as meat grinders or even mortar and pestles can also be used for grinding.
Ground food also has a much finer and often powdery or paste like texture with less individual particle definition.
Chopping of foods results in the food having larger and more defined pieces, while the grinding produces much smaller and often indistinguishable particles.
Chopped food also retains more of it's original texture and ground food has a smoother more uniform texture.
Chopping of food is often used for general food preparation and ease of cooking and grinding is often used for flavor release, specific textures or even to prepare foods for certain types of recipes.