The Pretérito Perfecto is used:
1. To express unfinished past:Todavía no he terminado. I haven’t finished yet. He vivido aquí toda mi vida. I've lived here all my live. The action began in the past and continues to the present.
2. To express experience:¿Has estado tú en Egipto alguna vez? Have you ever been to Egypt? The action happened in the past but we don't know when or we 're not interest in when.
3. To express the present result of a past event: María se ha roto una pierna. María has broken her leg. The action happened in the past, usually the recent past with results in the present.
Some of the time expressions found withthis tense are: esta mañana, este año, todavía, nunca, ya, últimamente, etc.
It graphical representation could be like this:
Pretérito Indefinido
The Pretérito Indefinido is used:
1. Instantaneous action. To express an action which happened at an specific time in the past and is now finished. Lo hice el año pasado. I did it last year.
It’s graphical representations could be like this:
2. To express an action that last for some time but is finished in the past an bears no relation to the present:
It’s graphical representations could be like this:
Some of the time expressions found with this tense are: el mes pasado, hace dos años, ayer, en 1983, el verano pasado.