0In simple past tense time is mentioned.
The adverbs used in the simple past tense are 'last week/last month/last year/a few minutes ago/ in the year 1987 etc.
Example: I met my friend in the year 2006.
We bought our house two years ago.
My friends went on a picnic last week.
Whereas, time is not mentioned in the present perfect tense. The adverbs used in the present perfect tense are 'since/for/yet/already etc.
Example: I haven't completed my homework yet.
I have been teaching online since 2016.
My brother has lived in the UK for ten years.
I have already finished the work.
She has not completed the work yet.
Since- point of time
For- duration of time
Already- Used in an affirmative sentence to show that something has begun in the past and continues in the present.
Yet- Used in negative sentences to show that the action began in the past and continues in the present.
Examples: My friend attended an interview last week.
There was an accident in our street yesterday.
We have not conquered corona yet.
Our government has found a vaccine for the virus.
