http://www.italki.com/question/82486 Poisonous Appleさんが本当に素晴らしい説明をしました＾＾

Well, basically "Hatarakimasu" is a present form and "Hataraiteimasu" is a present progressive form. But when we actually use them, we use "Hataraiteimasu" as a present form and we say "Hatarakimasu" as when we want to refer to the future. For example... "I work as a teacher." when you translate this into Japanese, you might say 「わたしは教師としてはたらきます。」 I can't say it's wrong, but it just doesn't sound right. We say 「わたしは教師としてはたらいています。」 "I'll start working from tomorrow." As for this sentence, we say 「わたしは明日からはたらきます。」 "I'll work until 8 o'clock today." this translation would be 「今日は8時まではたらきます。」 hope you could get the idea of these differences.

"Hagarayiteyimasu " means working. "Hatarakimasu"means to work.