If I understand your question, Ava, you are asking whether there is a difference between a one time exposure to very loud noise (explosion) and long term exposure to loud sounds (being in a combat zone or working in a very loud factory). If that is correct, from my limited knowledge in some circumstances our hearing can recover from a one time exposure (explosion). Sustained exposure to the loud noises are much harder on our bodies and brains. In most cases, this type of exposure can cause nerve damage. This coupled with other health issues may become progressive.
I sincerely ask you to speak to your hearing professional about this. There are many variables within each of the exposures you proposed that could affect the long term outcome. Please, talk to an Otolaryngologist or Audiologist and discuss the finer points of your question thoroughly.
Best, L