Sometimes the apprentice or intern is also paid in money. Sometimes the apprentice or intern pays. Often, no money is exchanged. Internships often involve office or administrative work, while apprenticeships usually focus on learning specific skills in a craft or trade. But many people use the terms interchangeably.
Apprenticeships can take place in any field, from chemistry research to interior decorating.
They've been around for millennia, though in recent decades they've been somewhat forgotten in the U.S. or at least restricted to certain trades. But homeschoolers have rediscovered them as a superb learning arrangement, and more recently, some schoolpeople have even started to set up apprenticeships for school students. In some countries, apprenticeships have always been the way that people learned certain types of work, but these fields are often stigmatized as the fate of people not brainy enough to become doctors or ambassadors or such. Unschoolers apprentice themselves for a week or five years, to chemists and museum creators and windmill repairpeople and poets. So, if you live in an area where people define apprenticeships or internships imaginatively, don't let them limit you dream up the best situation for you and for a skilled adult you admire, and then explain you dream and suggest a trial period.