As a lay person in this field, it depends on the education and training of the person.
"Clerk" is someone who has obtained the JD degree, probably has passed the Bar, so they would be given the most difficult work, and perhaps coordinating the work of the others. Presumably, the clerks will migrate into their own practicing attorneys.
"Intern" is probably someone still in school (either college or Law school). I would expect them to get the lowest level of work
"Paralegals" have probably completed a Bachelor's degree, and have taken / completed a shorter, not as thorough study of law and the procedures in court etc. The middle level between Intern and Clerk.
That's a pretty good summary of the terms.
Clerk is really wide open as a term, as they are all over the court administration business. But a judge's clerk generally has the JD (degree), and may or may not have passed the bar. I clerked as a law student for three law firms in school (one at a time). I took the bar before being a MI circuit court judge's clerk, got the job, then found out I passed the bar later. Circuit court is trial court, so I was both bailiff to all jury trials, and law clerk doing research and writing on matters pending before my judge. I also got deputized as a county sheriff for arrest powers in the courtroom (and a little better immunity from civil suit). But no gun and no cuffs, just a firm grip and a small lockup. Fortunately, there was not a lot of that. I had to take possession and secure physical evidence admitted during trials, including guns, bullets, brain tissue, dead guy photos and other stuff. They would not let me take possession of the 20 pounds of weed though.
I interned for a MI senator, and a city manager/mayor in undergrad. Interns aren't limited to legal, they are like apprentices to many occupations.
Paralegals (generally a 2-yr associates degree) do office work, typing, dictation, court filings, law librarian work, hunt and interview witnesses, gofer, and nuts and bolts legal work. Paralegal are a also military occupational specialty in the Judge Advocates Corps of each branch of service (mostly NCOs).
Clerking for the Supreme Court is a very big deal. Those judges use their clerks how they see fit. And there are senior and junior ones. They read, research, organize, check accuracy, and write opinions (or parts of them) for a judge to read and use, or even sign.
About a thousand people apply for clerkships with the U.S. Supreme Court each year, and most if not all have stellar academic pedigrees from top universities. About 36 make the cut.I worked with a gal at USDVA who had clerked for Ginsburg. Very smart, and very liberal.
