An adjustment could also be deemed a compromise. It just depends on what is the subject, and why was an adjustment suggested?
Also, an agreement could be made by giving concessions, or adjustments. The goal of doing so would be to get an agreement.
Compromises don't really create good agreements. A good agreement is when both sides match either by giving more on their side, while asking the other side to take less. Is this a compromise, a concession, or just being fair.
An adjustment could also be a mechanism to make up for an error, say in math, or for a service that wasn't all successful. For example, it turned out that a cheaper, or more expensive part went into the project. The adjustment would make it right without scrapping the completed project.
much of it can be just semantics.