The Start Internship is an internship for freshmen and sophomores who are interested in one of PwC's divisions and are able to get a "headstart" and really see if the company works for them. The company values interns because hopefully, you will come to work for them. The Start Program is seen as a Diversity internship; it is an important outreach for the firm and they provide various support services and affinity group events. However, since Start interns are not interning after their Junior Year of college, you may not get as much work, but it really depends on your manager.
Here goes the official description of what a Start Intern is and does (https://www.pwc.com/us/en/careers/entry-level/programs-events/start.html) but in my own words I would describe the program as half shadowing/non-client facing work and half working in internal firm services (IFS). First and foremost there is no actual client work but you are assigned to teams to shadow or do non-client facing work. Through shadowing teams you are able to get a glimpse as to what it is like to be a full time employee as well as the different lines of services that PwC has (assurance, tax, and advisory.) Your work with an IFS team focuses on internal firm services such as marketing, infrastructure, or technology. My specific experience was in marketing.
First of all, the Start Internship is geared towards those students who identify as a underrepresented group in accounting including African-American, Native American, Pacific Islander, and Latino. Start Interns main goal is to get enough exposure and build enough connections to be able to select a service line by the last week of your internship. You will shadow in audit and tax to gain that exposure and those connections, but it is ultimately up to you to make the most out of your time.