Hi Jay...The first tense indicates that the action is completed. The second indicates that an action started, but didn't end, when the next action took place. Estuve is somewhat simpler. It is the past tense. Example: Estuve en clase (ayer, anoche, hace tres meses, anteayer.etc.) It means that it is in the past. That's it. It happened. Estaba is used to indicate that a past action is continuing or it was in progress during the time of the action. Example. Estaba en la casa cuando ( me llamaron, empezó a llover, etc.) The fact that you were in the house didn't change or end because you received a phone call or it started to rain. Another example of the verb tense with a different verb would be: Leí el periódico. Leía el periódico. The first one means that you read the book. You finished at the time you made the statement or you finished at the time you were referring to. The second means that you were reading the book but it doesn't mean that the action is complete. Like, I was reading when she called. The second tense has other uses as well. It can translate to "used to" as in English. For example: Cantaba todos los dias. It translates to "I used to sing everyday." Hope this helps..