I once posted the difference between ‘desu-yo’ and ‘でしょう’. please take a look at the ex4, 6 below. when you ask a question using でしょう,　you want to make sure what you have guessed or want to have them agree with you. 　The phrase desu-yo is used when the speaker is telling some info that he knows(ex1). Meanwhile, deshoo is also used when the speaker is telling the info that is not completely certain(ex2). When you want to say the sushi you ate was good, you say 「おいしかった ですよ」 instead of「おいしかったで しょう」. １． ×私の家族は５人でしょう。 ○私の家族は5人ですよ。 ２． 明日は雨でしょう。 　Sentence-ending intonation　refers　to　the　high　or　low　pitch　of　the　voice　 at　the　end　of　a　sentence.　 When　a　sentence　ends　with desu-yo, the intonation can rise of fall, without much difference. However, when a sentence ends in deshoo, the meaning is changed by the intonation. ３．a ひらがなとカタカナ、どちちが むずかしい？ b たぶん、カタカナでしょう。↓ ４．a 漢字はむずかしいん でしょう。↑ b うん、はじめは むずかしいね。 In ex3, deshoo is used to tell some info that is not certain. However, deshoo is used with rising intonation when asking about the other’s opinion, or reconfirming the info. In ex5, the speaker has the info. on the contrary, when the listener has the info, it goes in ex6. ５．あそこで買うと安い ですよ。↓ ６．あそこで買うと安い でしょう。↑ good luck.