in.liggghts_init vs. in.liggghts_resume

Dear all,
I am trying to set up a simple simulation with particles settling in stagnant water.
To run the simulations I need both in.liggghts_init and in.liggghts_resume. What is the role of these two scripts respectively.
If I change for instance the timestep or the dump in in.liggghts_init, it does not affect the simulation. It appears that the simulation is reading these settings from in.liggghts_resume. Are they then needed in in.liggghts_init.
Thank you in advance
Best regards
Bjarke