Grave field are cemeteries with no above ground structures (such as gravestones). Maybe we separate cemeteries with gravestones from grave fields.
Tumuli have a mound above them, they are a type of a cemetery, but different from grave fields.
But not quite what the Wiki "definition" of "Grave Fields" describes - https://en.wikipedia.org/wiki/Grave_field
It actually defines a tumulus field as being a "type" of "Grave Field" based on burial custom.
It also lists Sammallahdenmäki as being a "Grave Field" despite the piles of "above ground" stones there! (I have checked the Nom File and the phrase isn't used)
The phrase seems to have particular (but not uniquely) Nordic/Bronze age application. I note that there is a Swedish word ""Gravfält" and I wonder if its use is "specific". eg. On Oland "Gettlinge Gravfält. Grave field at Gettlinge. Gettlinge Gravfält is one of the largest and certainly most beautiful prehistoric burial sites on the island of Öland"
We were in Tamgaly a couple of years ago and it has an area of bronze age "graves" with little or no above ground signs - but it ALSO has things called "Kurgans". Its Nomination File. The phrase "Grave Field" isn't used however in the Nomination File ut Wiki includes "Kurgans" as "grave fields"
In wonder if the phrase "Grave Field" is used specifically enough for us to try to categorize examples of areas containing graves as between the other possible words for them - cemeteries ,Tumuli, Necropoleis etc etc