I have worked at a company for 6 years. Some months during the beginning of my career, I was on a paid internship with the same company.
During my internship I had the same duties (same projects and kind of job) I also had after my internship. The only difference is that I wasn't responsible for my actions cause I was "in training" and the chief engineer was my supervisor.
I have a section on my resume "work experience" that lists all the points of my experience, sorted by company name. As long as I didn't have different duties during my internship, I'm not sure how to write that because I can't distinguish some different kind of skills I developed during that period.
So, is it okay to just put a line like "internship" with a "Junior" title or "in training" or something like that in that case?