I wrote this a while back
Once an application has reached a school there are 3 different phases done by 3 different people or groups for 3 different goals
1) Screening: Also can be referred to pre-screen, initial review, early review, etc. This is done usually by adcom (office) staff and/or readers/evaluators to sort, classify, and assign applications to evaluators and/or teams/subcommittees on broad criteria and priorities. Initial academic metrics (GPA/MCAT), URM, alumni, linked programs, feeder schools, and other items can have an application moved up in the queue for processing and evaluation.
2) Evaluation: This is where a reader and/or group of readers fully analyze and evaluates an application. Since schools get thousands of applications, all the evaluations will be recorded an what is known as a cover sheet, summary sheet, evaluation sheet, or similar which will usually have some kind of scoring and/or classification system for each part of your application. This may assign categories from Outstanding, Excellent, Above Average, Average, Below Average, Subpar, Not Qualified or a system that assigns points that are then added and given an overall metric. For example, GPA, school selectivity, difficulty of program, grade trends, post bacc, MCAT subscores may be given points added to an overall academic metric or score. Additionally, your application may be broken apart and evaluated by different people and brought together in an overall score that would best be seen as your review priority. They may evaluate each part as they come in This may have intermediate steps of a subcommittee and predetermined criteria that certain score levels are granted interviews before the next step
3) Review: This is where the adcom meets and reviews each applicant for interview. and this where is where applications must be complete (primary, secondary, MCAT, LOR) prior to review. Application may be presented by the primary reader/evaluator, by the subcommittee chair, the adcom staff, or just reviewed as they come up. Applications that receive higher priorities in the evaluation step are likely to be scheduled for review first. Since schools get thousands of applications presenting large workflow, lower priority applications may take several weeks or months to reach review and possible interview invite.