Él, ella, usted
Ellos, ellas, ustedes
The difference is that Estar is used to indicate a "state" of being:
- location of things or people (but not events!)
- emotions (moods & feelings)
- mental conditions ("I'm confused")
- physical condition or appearance ("I'm tired" or "You look nice today!")
- motion (the Present Progressive: "I am in the current state of drinking coffee and typing.")
|Newark está en California.||Newark is in California.||Location|
|Estoy en la clase de matemáticas.||I'm in math class.||Location|
|Estoy enojada.||I am angry.||Emotional State|
|Estoy contenta.||I am (feel) happy.||Emotional State|
|Estoy cansada.||I am (feel) tired.||Physical State|
|Estamos bien.||We are (feel) fine.||Physical State|
|María está bonita.||María looks pretty.||Physical State|
|Estoy escribiendo.||I am (in the middle of ) writing.||State of Motion|
Notice when indicating physical location, Estar uses the physical locator preposition "en." En means "in", "on" and "at" in English when referring to where things "are physically" (but Estar cannot be used when saying where events "take place" or "occur" as they have no physical form. See Ser for events and other time-related uses.)
Students often ask me why Estar is used when saying someone is dead: "Mi perro Fido está muerto." This is because it is a physical state of being: Just like being sick or well, tired or energized, your body can be dead or alive.
You may have heard that Ser is used for things which are permanent and Estar is used for things which are temporary. This is an over-simplification and not a good way to think of these verbs because you will end up with a lot of exceptions and confusion. Try to forget you ever heard that.
Remember instead the above designations Estar covering States of Being: Conditions, Location, and Motion (the Present Progressive) and that Ser is used when expressing elements of Identity.