Your resume is meant to tell a story, so you’ll want to list ALL your “experience” chronologically, in one section. You’re painting a picture of yourself to the hiring manager, and the goal is to convince him that a) you’ve got the qualifications to handle the open position, and b) you’re an organized, motivated, responsible person who will get the job done. If you’ve completed internships or performed volunteer work that can demonstrate these qualities, you should include them as part of your resume story. Putting internship experience in a separate section diminishes the importance of the work you did at each company and suggests that you didn’t learn anything during the internship. The same goes for college leadership experiences – if you’re lacking professional experience in the field but have taken on meaningful roles during your time as an undergrad, you can include them in your resume timeline to help tell your story. You don’t need to break these out into a separate section – any type of experience counts for something, regardless of the context.
Second, having multiple sections suggests that some of the positions you’ve held are less relevant to the job you’re applying for than others (especially when you title one section "relevant experience" and another "other experience," which is basically code for "irrelevant experience"). As we’ve said many times, you always want your resume tohighlight the responsibilities that are most pertinent to the job you’re applying for. You’ve got limited space on your one-page resume, so why would you waste it by listing extraneous positions (and calling attention to them by giving them their own section)? If there’s a gap in your resume timeline, you might need to fill it in with whatever you were doing at that time -- carefully crafting your bullet points to showcase skills you learned there that will be helpful in the position you’re applying for -- but that gap explanation is actually useful to the person reviewing your resume. In general, if you have enough related experience, you don’t need to include your freshman year job at Starbucks or that you were the president of the modern dance club in college, but if you don't have any other experience, you can pull the transferable skills from Starbucks and club leadership, making those seemingly "irrelevant" experiences relevant. Once you've built up more professional experience, you can remove the college leadership activities and volunteer work (or internships) outside the industry from your resume. You’ll eventually get to the point where you don’t need to list any internships or college experience on your resume, but until then, be proud of what you’ve accomplished, and showcase it all in a clear way.