Notice that the first and the second sentences have the present tense. However, the second sentence differs from the first sentence in that it expresses the future event with the time adverb 내일 “tomorrow.” The third sentence uses the probable future ending -(으)ㄹ 거예요. Notice that the possibility that the future event (e.g., going to Korea) will occur in the future is less certain in the third sentence, when compared to the second sentence. In other words, -(으)ㄹ 거예요 indicates “a probable future event” rather than “a definite future event.”