The SpaceX Starship (lunar and/or crew-rated version, upper stage only) is expected to have more habitable volume than the International Space Station. On the other hand, the ISS is around 400 tons, while the dry mass of the Starship is more like 100 tons (rounding to one significant digit in both cases). Now, some of that extra mass is likely down to the fact that short, fat cylinders have a better volume to surface area ratio than long, skinny cylinders. But it also seems plausible to me that a lot of the ISS mass is dedicated to functions beyond habitable space and propulsion, the two things that an orbital Starship would do extremely well. (One possible example: docking lots of ships at once.)
Hence my question:
If we put a human-rated Starship in orbit and tried to use it as a space station, what significant engineering capabilities would it lack that the ISS currently has (and takes advantage of)? Also consider whether the capabilities could be met another way: for instance, a Starship-station would not need the capability to run decades-old computer hardware.
By way of analogy: if the question were "What can a Google Datacenter do that a warehouse cannot?", a good answer might mention the need for massive amounts of water and electricity, as well as ventilation and any structural requirements that might be needed to support racks of processors. Essentially, what would Google look for if they were considering renting a building to house their datacenter? In the same fashion, what would a government look for if they were considering hiring an orbital spacecraft to house their people and experiments long-term, and which of these requirements would an off-the-shelf lunar or Martian Starship lack without significant modification?