I will be in Japan in a few weeks and I am trying to learn the basic to be as polite as possible.

One of the first things I did was try some basic stuff with Google Translate but I feel lost already.

When I try to translate hello from english to japanese I get: こんにちは

When I try Hello I get: もしもし

Why is there a difference, is this a Google issue or there is a real difference between both? Which one should I use to say: Hello

Thanks!