Hello Lal,
Let me put it this way:
There are 31 realms in which one can possibly be re-born due to Kammic energy, i.e, one’s actions past and present, in any of these 31 realms there will be some level of suffering, therefore one should strive to end the wheel of Samsara by purifying one’s mind to attain saupadisesa nibbana. At the time of one’s death, providing the saupadisesa has been reached prior to death then one will reach full nibbana.
Ok, now, let’s assume I went thru these steps, I attained saupadisesa Nibbana, I just died and attain full nibbana, obviously being dead, I ain’t going to jump over puddles or anything funny right?, I’m dead AND in full Nibbana so why am I called an Arahant and the Buddha is called a Buddha? Please don’t hold back on your answers!