Какая разница в переводе fill in и fill up

fill in - заполнить (например fill in the emprty spaces - заполнить пустые места

fill up -  наполнить  (например fill the jar up with water) - наполнить кувшин водой

fill in заполнять

to fill in a form — заполнить бланк

i'm just filling in here temporarily. — я здесь только временно замещаю другого.

how am i going to fill in this afternoon now that he's not coming? — ну и что мне теперь делать во второй половине дня, раз он не придёт?

fill up больше замещать.

boss is on vacations, i'm filling up for him. — босс в отпуске, я его замещаю.

my family travels a lot. we visited a lot of places. once we visited new-york. we got there by plain. it was the city which never slept and the city of the skyscrapers.   we visited a lot of attractions. we walked in a famous central park which was used in many hollywood movies. i saw three major airports of the country. this place contained the most complex network of subways in the whole world. there were a lot of hotels and restaurants.  in the evening we walked in the streets and saw different interesting people and places. it was great. i will never forget my journey.

a: did you hear about that train crash last week?

b: yes, terrible, wasn't it ? ten people killed! they say that if the train operator had  reacted  more quickly the train would have  stopped  before it reached the level crossing.

a: well it was the   lorry-driver's fault after all. there  wouldn't have been  an accident if the lorry  hadn't broken down  on the level crossing.

b: it says in the paper that if the driver had  telephoned  the signalman to let him know the signalman would have  stopped  the train until lorry had been moved. then the accident wouldn't have happened  at all.

a: if i were  the lorry-driver i hadn't tried  to cross at that level crossing anyway. i  would have driveved  to gloucester and  crossed  the railway by the bridge.

b: well there's nothing we can do about it now. but those ten people wouldn't have died  if the lorry drive had been  more careful.