There will be nutritional changes but not super significant. Pressure cookers do a better job at breaking down peptides vs boiling and slightly better mineral extraction from the bones but the overall macros and micros are going to be very very similar. It might not look like anything has happened to the cartilage when boiling but you are still extracting lots from it.
The big benefit of pressure cooking bones is that it cuts the time to make broth to something not measured in hours and you don’t have to check on it all the time.
I’ve been wondering about this myself - I keep trying to make broth in the instant pot, but when I do it doesn’t get gelatinous like boiling on the stove top does. It does seem like the bones fall apart easily and the skin is thin/delicate/falls apart.
Does your instant pot broth gel in the fridge?