Take these two sentences:
하는 거예요 and 해요.
Or how about 좋아하는 거야 and 좋아해? Both mean "I like (something)," but there's a difference in how they're used and you might prefer one or the other depending on the situation.
What's the difference? In the video I talk about this, but the main difference is the nuance of each form. Both the ~것이다 and the regular ~요 form can be used to have the same meaning, but the ~것이다 form gives a stronger emphasis on the subject while the ~요 form gives more of an emphasis on the verb. Find out more about what I mean by watching the video below.