I think you could also translate this one as "small apples are sweet"... the whole sentence is simple present tense and requires context for meaning in korean.
great job with the new Korean language program, but some small things still need to be cleaned up. like they put jag un to mean sour and it means small. I lived there for eight years they just don't ever use jag un and no dictionary has jag un to mean anything but small. There for I put the small apple. or the apple is small.
작다 means small, indeed.
The point you are missing is the meaning of the verb 달다. This translates into "to be sweet", not "different" (다르다). The latter would be conjugated as 달라요. Notice the additional ㄹ.
Can there be some way to accept a synonym? I put "The little apple is sweet." That really means the same thing as small.