It depends greatly on local traditions and beliefs. It also depends on where you are geographically

Norse societies were not a single United entity and culture. I stead, you should see it more like a few hundred or thousands individual cultures roughly sharing the same aspects.

Ibn Faldad, when visiting the Rus, wrote that they burned the bodies in boats so that the dead could join his fellow in the afterlife, instead of throwing them in the dirt and letting them rot to the beasts like you do in the south, one man apparently told him. That means that the Rus believed in a spiritual meaning behind Cremation

However, if you take the example of Oseberg, you see that someone as important had access to similar rites, but without a cremation. That means that people in this place did not believe the same as their eastern european cousins did. Yet, if you go a little north, the Gjermundbu grave is an example of cremation. Probably did they believe something else in that different place? Also, Gjermundbu being inland, it's a bit more tricky to be buried or cremated in a large ship

A good example, a bit off topic, to show that difference within beliefs would be the cult of Thor. Historians have noticed that, the further north you go, the less evidence (in archaeology and place names) you have of a cult to that god than in the south, which was fairly strong. This shows how different the rites, beliefs and culture was in Norse societies.

Typo, doubt was meant to be found. Don’t know why it autocorrect like that

Correction: the mounds typically did not have stones around it. There was a forth type of funeral that had the ship and body buried level to the ground, in which case stone would be sitting on around the ship outlining it