[JusTGo]

does both codes do the same thing if not whats different between them:
#1

PHP Code:

#include <hamsandwich>
#include <amxmodx>

public plugin_init()
{
    RegisterHam(Ham_TakeDamage, "player", "TakeDamage_Pre");
}

public TakeDamage_Pre(iVictim, iInflictor, iAttacker, Float:fDamage, iBitDamage)
{
    HAM_SUPERCEDE
} 


#2

PHP Code:

#include <hamsandwich>
#include <amxmodx>

public plugin_init()
{
    RegisterHam(Ham_TakeDamage, "player", "TakeDamage_Pre");
}

public TakeDamage_Pre(iVictim, iInflictor, iAttacker, Float:fDamage, iBitDamage)
{
    SetHamParamFloat(4, 0.0);
} 


[safetymoose]

Supercede blocks the damage completely, and in the second code you change the damage to 0...

[georgik57]

supercede will completely block the damage event(no blood will come out, victim won't be knockbacked, etc), while setting the damage to 0 will just not substract hp from the victim.