So how would the styles differ in reality? Well, in terms of how the person comes across someone who is assertive will be self assured and will display a calm and even temperament. Someone who is aggressive will put others down or will be sarcastic. They will be volatile and unpredictable. A passive person will be apologetic and will put themselves down or be timid. They may be flustered or emotional as they are taken advantage of, but don't have the tools to put this right.
Secondly, an assertive person will express their feelings and will feel and appear comfortable in social situations. Someone who is aggressive may appear defensive or uses put down and bully tactics. A passive person may be anxious and resentful. They can come across as frustrated and may experience irrational fears. Finally, an assertive person will choose whether to accommodate negotiate, compromise or refuse and will appear approachable whereas an aggressive person will manipulate as far as they are able to. a passive person will accommodate others at their own expense and will allow others to make decisions for them.
An aggressive person will aim to get their own way regardless of others and can appear intimidating. A passive person can be shy or withdrawn at times and may feel worthless or useless. They feel they cannot assert themselves. As a result, an assertive person will achieve their goals without hurting others, an aggressive person will achieve their goals regardless of others and the passive person will generally not achieve their goals. They will feel pushed and pulled in different directions.