Does UPMC and The University of Pittsburgh have anything in common besides the name? It's affiliated by name, like a branding partner, but seperate entity right? Or am I wrong? This has always confused me.
Short answer yes: legally separate entity, but closely affiliated.
A slightly longer answer written by administrators at UPMC that actually published an academic article on the system: It is a mutually exclusive partnership of close affiliation formalized by a series of interrelated agreements and mutual executive oversights, which includes the sharing of numerous board members. This created a collaborative and coordinated decision-making model in which UPMC oversees all clinical activity, while the University of Pittsburgh remains the guardian of all academic priorities, particularly faculty-based research
Now, I'll fill out some more info starting with a shortened version of the history. The reality is, UPMC is technically and historically a Pitt spin-off company.
1920 Plan for the "University Medical Center"
The "University Medical Center" in Oakland was gathered and developed by Pitt over the course of 60 years starting back to 1910s, and slowly consolidated the hospitals together so by the 1980s they were merging into Pitt's Medical and Health Care Division. By the end of the 1980s, once Presbyterian University Hospital and Montifiore hospital merged, the name was changed to the "University of Pittsburgh Medical Center." Then to gain leverage against Highmark's insurance monopoly in the 90s, it formed the Tri-State Health System with hospitals outside Oakland...like St. Margaret's, Passavant, etc. They all soon merged together and they started their own health insurance subsidiary.
By the end of the 90s, UPMC was getting huge but it wasn't entirely financially sound, and it was in a fierce battle with ARHEF (which was actually larger at the time) and there were all sorts of scary changes coming down the pike with medicare reimbursements, etc. The massive bankruptcy of ARHEF was far from predictable at that point, but also illustrates the real danger some medical centers were facing (and still face).
What Pitt did was look at the logic of the head of medical center reporting to the Chancellor, and it effectively made no practical sense any more. The Vice Chancellor of the health science should not be running a giant medical system. But a big concern was the financial blow back from the risks UPMC was taking (and really all academic medical centers at the time) as it was growing and engaged in fighting fierce battles in its market sector, so there was a desire to create a financial firewall between the two entities in order to protect the university.
So the medical center was spun off, which took some serious untangling and exchange of various components, but the end result was two independent legal entities that are very closely affiliated and that includes shared governance and shared missions. Essentially, UPMC assumed control of all clinical practice aspects and all of Pitt's physician practices of the faculty in the med school. So all Pitt's medical faculty practice their clinical specialties in UPMC. Pitt retained all control over academic research, so all research grants are handled by the university and the faculty are professors and teach at Pitt. They get paid for their academic work by Pitt, and reimbursed for their clinical service by UPMC. (This isn't true of a doctor at UPMC Altoona, for instance, which is just an employee of UPMC.)
The governance is shared too. UPMC board of trustees is split 3 ways: 1/3 representatives from Pitt, 1/3 representatives from the Pittsburgh community at large, and 1/3 from their subsidiary hospitals. I believe UPMC's charter states that a mission is to benefit/support the university, and it does this in droves. UPMC pays a deans tax to the medical school, along with additional academic support, research support, etc. Essentially, these agreements with university run on 10-year contracts.
In FY15, UPMC's support to Pitt's med school was $190 million. That is an enormous number, more than the Commonwealth provides to the entire university, and absolutely more than any other medical school in the country gets in support from its affiliated medical center. If you wonder if there is an interest in UPMC doing well among Pitt supporters like me, this is the clearest and most tangible reason.
There are all sorts of intertwining collaborations between the two entities. If fact, things you may not realize, like the Carillo Street Steam Plant behind Trees Hall is a joint UPMC and Pitt project. Pitt and UPMC jointly operate the Medical and Health Sciences Foundation to fund raise for medical research and projects for both. There's the Pitt Cancer Center/UPMC Cancer Center collaboration. They're collaborating on starting a giant research institute in Italy. There are too many to list.
So yes, they are legally separate, but they are entangled like the snakes on a caduceus.