Achievement is the act of reaching a goal.
For instance, graduating from 8th grade or high school is an achievement as is being selected for the football team or making a high grade in a class. A desire for achievement is normal is normal for humans, but for some people the desire for achievement becomes a "need," not just a desire that can cause a person to continue to push themselves further and further.
Need for Achievement ( also referred to as n Ach) is the degree to which someone is motivated to set and reach goals. Coined by Henry Murray, individuals with high n Ach are usually driven to succeed for internal, personal reasons rather than by external pressures.