In English there is a clear difference between the sentences.
I have swept the floor. (ie a recently completed action)
I swept(did sweep) the floor. (An action completed sometime in the past)
In the first case there is no need to express a time of when the action was completed whereas in the second case there does not need to be some time expressed.
I swept the floor yesterday/this morning/at 4......
The same difference occurs in Welsh.
There is a possible subtle difference of implication dependent on context, but in many cases not a clear cut difference in meaning in English. If your partner arrives home and you say "I swept the floor" it implies something no less recent, and requires no explanation of what time in the past it happened.