How are they different? In either case you have an end result that is clean. The difference is in the moment of the cleaning, but that is not indicated in the scripture you cite.
Though I’ll not take time to search the dictionary for you, I’m confident that it shows “conceived” has not the same meaning as “cleansed” despite your claim that it’s just timing.
“The difference is in the moment of the cleaning, but that is not indicated in the scripture you cite”
That statement makes no sense.