When you are hired as a co-op work term student or an intern, you are in a special situation and it is important to understand the context in which you find yourself. A different hiring process was used to start with, and in many cases students are hired with literally minutes of 'investment' versus the long process a permanent fulltime employee might be subjected to. Once you start work, you are also in a different situation compared to the average employee.
The jobs and tasks will change from your first work term to your later ones. As you learn more about how to be a valued employee, your jobs will likely improve. If you can return to an employer with more responsibilty and decision making, the jobs will also be more rewarding and enjoyable.
You have to remember that on your first work term, you are marginally more useful than a high school graduate! Sorry, but think about it. You have had some more courses and have learned some more facts and hopefully started on some skills, but that is not that much. As you have more work terms, you will have hopefully learned more things that the employers value and can make use of.
When you start, you will have limited experience, knowledge, and wisdom about the company, company culture, products/services, etc. compared to the established, long term work force. Perhaps a 1-2 on a 10 point scale. It can take many months or years to REALLY understand what is going on in large companies or complex situations. Never forget what you know and do not know - and be careful about making assumptions about situations you know little about. Do not suggest or recommend things until you 'understand' what you are talking about.
Fulltime employees are recruited and hired through a wide range of hiring processes, and future career options/paths, immediate and future roles, etc. all come into play when a position is posted and the hiring process starts. Coop and internship positions might be posted 4-6 months before a student starts and sometimes the role is well defined and known at that time and in other cases, they think they will need a student, might not be too sure what the student will be doing, who the student will be working with, but will sort it out when the student arrives at the door.
Fulltime employees are usually working on a long term career plan, path; trying to get promoted, get bonuses, etc..
They are often in a training program when they are hired - depending on the company and postition hired into. Their training can last longer than your work term or internship!
They will be impacted by decisions made long after you are gone - they have long term investments in the game and must live with theirs and others' decisions.
As a teenager or 'just turned 20 something', you might experience a certain tolerance, helping, and mentoring that fulltime personnel do not get. While everyone is expected to be professional, mature, responsible, and accountable, your co-workers might understand that you are learning these things and give you some slack.
Your actual tasks might be different as you are an unknown and unproven commodity. You might not be given the critical or priority work to do until you understand the company, what is going on, what is needed to be done.
Since you are there for a relatively short time, your tasks will probably have a limited scope - to be started and completed within the work period.
You might be given one thing to focus on instead of multiple tasks.
You will not probably be on the critical path or be the bottleneck in a process - until you have proven potential, skills and can be trusted with important work.
You might be given tasks that the fulltime workers are too busy to do or that would not be a good use of their time - diving into new or potential topics, testing the water, doing a prototype, proof of concept, helping to explore risks.
Your opinions and thoughts might be heard, but that does not mean that they are good ideas (some will be), that they will be used, or that you have a real voice in the decision making or that you will be in meetings where the real decisions are made.