Hanafi and Shafi Asr times
Asr is the only prayer where the two methods disagree. The Hanafi time is later. The rest of the timetable is the same.
The shadow rule
Asr begins when an object's shadow reaches a set length. In the Shafi method that is one time the object's own height, on top of its shadow at noon. In the Hanafi method it is two times. The longer shadow takes longer to form, so Hanafi Asr is later.
How big the gap is
It is usually between 30 and 90 minutes. The gap is smallest in summer and largest in winter, and it grows the further you are from the equator.
Which one to use in Pakistan
Most mosques in Pakistan follow the Hanafi time, so calendar.pk uses it by default. You can switch to Shafi on any city prayer page, and the choice stays in the link you share.
Common questions
Which prayers change between the two methods?
Only Asr. Fajr, Sunrise, Dhuhr, Maghrib and Isha are the same.
How many minutes apart are they?
Usually 30 to 90 minutes, depending on the season and the city.
Which does calendar.pk use by default?
Hanafi, because it is the common choice in Pakistan. You can change it on any prayer times page.