A certificate of achievement acknowledges both short- and long-term accomplishments. It does not necessarily signify that a person has completed something, but hit a significant milestone in the process of completion. For example, a child can get a certificate for "Best Team Player" at a basketball camp, even if she hasn't completed the entire camp. A student can receive a certificate of achievement for "Best in Creative Writing" although he might not have finished his creative writing class or the school year. Similar certificates can be given in the workplace. These certificates hold varying amounts of weight when attempting to advance in the educational sphere or workplace, but are in no way equivalent to a diploma, raise or increase in responsibilities.
A certificate of completion acknowledges that a person has completed something from beginning to end. For example, a person could have completed a school year, an important test or exam or a certification process. Certificates of completion recognize that a person has gained experience and skill that she did not have previously. These certificates can be used as proof of skill and experience in both the educational sphere and the workplace.
Certificates of achievement hold little weight in the educational sphere. As a student accumulates these certificates at the high school level, he can use them to appeal to a college recruiter in his application process. Certificates of completion are comparable to diplomas in the educational sphere, but are not equivalent. Rather than allow the student to advance to college as a diploma or GED would, a certificate of completion is an acknowledgment of that student's work from the beginning to the end of the year. It holds no weight when applying to colleges and does not mean that the student has passed all of his classes. It will at most allow him to walk the stage and participate in other graduation ceremonies with his classmates.
Certificates of achievement in the workplace are nothing more than kind acknowledgments. They serve to make employees feel appreciated and noticed for their hard work, but they do not mean that the employee will advance in any way. In the educational sphere, a certificate of achievement similarly holds little significance besides acknowledgment and motivation. Until a student reaches the high school level and is ready to apply to college, she is unlikely to find a place to use those certificates for advancement.