Grammar - difference 2
study ex 1 ex 2 ex 3 ex 4 ex 5 ex 6 ex 7 ex 8
 

Use: past simple

Use: present perfect

Finished action in the past
They cut down trees to build this skyscraper.

 Present result of past action
 They have cut down trees to build a skyscraper.
   

Given time
He flew a balloon in London in 2003

 Time is not given
He has flown balloons before.
   

yesterday, last summer (week, month,...), 
ten years (weeks, days, minutes,...) ago
The family ate one hour ago.

  this morning (year, month,...) just, since,
for, ever, never, yet, already
The cat has just eaten the cuckoo.
   

A past action when time is understood.
Elvis wrote a lot of songs.