In Difference between^x, barn^x

Thank you very much, because I searched for the translation from portuguese 'celeiro' to english and they translated as granary, though I never had seen that word before, well barn I have seen before related to a farm..

I tried to translate a word that is related to farm, a house where farmers keep the food the collect, and I came to words barn and granary... Is there a difference between those words? what is the most common word of the two? the one more people know about?