Part-time job: refers to the use of spare time to engage in a second occupation (students are studying) without leaving their jobs;

Internship: You may still be at school, or you may have just graduated and never worked. After the internship period, you can become a full member as your main job.

Summer/winter vacation: refers to people who engage in certain jobs during the summer/winter vacation, mostly students; It is a period of full-time work. If you leave your job, the company may need to find someone else to do your current job.