Usted or Tu?
Again it is confusing how to use these two different words. They seem to be the same, but there obviously is a difference. When should I use one over the other?
Usted is "formal singular you", it shows respect and distance. Tú is "informal singular you", it shows closeness.
As a general rule, your parents, friends, spouse and children are "tú". Your boss, older strangers, clients, teachers, etc. are "usted". However, it varies depending on dialect, age and other things.
One way of thinking about this that often gets fairly close to how tú and usted are used is if you think about, in English, if you would use the person's first name when talking to them or if you would say Mr. or Mrs. Smith or whatever.
Like I said, this isn't true in every Spanish speaking culture, but it comes pretty close to describing the custom in some.
It even holds true in some cases where the age is very different. I remember as a teenager I had a neighbor who was 60 years old or more, and a very respected member of the community. He played the organ professionally at our large church, for example. I always called him Mr. Boonstra while I was growing up. However, at one point I became very interested in organ playing and he would let me play the pipe organ in his house. Well, with that, he started to insist that I call him Sam. I didn't at first, but as he kept insisting I eventually did. The same thing can happen in Spanish, where the elder señor requests: Por favor, tutéame. This is showing that despite a major age difference or status-difference that the person wants more familiarity, wants to be more like a friend. This is called "confianza" in Spanish, which can mean trust, but in many cases mean more like "feeling close, being familiar with someone" etc. Being friends.
You should usually use "Usted" just because is more respectful, but with friends or people younger than you is ok to use "Tú".
I live in Mexico, and I usually use "usted" just with older people! But is just different because of the respect you show to the person you're talking to!
Hope it helped!