Athinu chance illa.... As per comics, both are different. If Lady Death is a blazing sun, Hela is a candle Light Dinner !!
Moreover, if Death is already dead, How can others die. There is already a comics series featuring death of Death. It was done to save previous Captain Marvel. Mad Titan will enter into that reality bringing death and destruction every where.
Anyway, The Cosmic Entities (Death, Entropy, Infinity and Eternity) created the Infinity Stones and had their likenesses portrayed on the walls of the Temple Vault on Morag. So it is unlikely that one among them is dead. There would be a power vacuum and balance-shift.