I'm trying to calculate the time difference between one hour from one day to the next day and get the result in minutes.

For example: from 10:00 am, 08/08/2020 to 09:59, am 08/09/2020 = 1439 minutes

var date_1 = str(status.dateTask.year) + "/" +str(status.dateTask.month) +"/" + str(status.dateTask.day) + " " + str(status.timerTask.hour)+":"+ str(status.timerTask.minute)+":"+str(status.timerTask.second)

var date_2 = str(dateCurrent.year) + "/" +str(dateCurrent.month) +"/" + str(dateCurrent.day) + " " + str(timerCurrent.hour)+":"+ str(timerCurrent.minute)+":"+str(timerCurrent.second)

var start = date_1
var end =   date_2
var diff = int(start) - int(end)

I am using this but the values ​​are not correct.

You need to convert both timestamps into seconds or minutes and then calculate the difference. Best to use unix timestamps for that:

var t1 = OS.get_unix_time_from_datetime ( { "year": 1969, "month": 3, "day":22, "hour": 10, "minute": 20} )
var t2 = OS.get_unix_time_from_datetime ( { "year": 1970, "month": 6, "day":12, "hour": 7, "minute": 3} )
var minutes = (t2-t1) / 60.0
print(minutes)
a year later