6. Cuando-Si llegue Rosa, dale el dinero del libro. Cuando llegue Rosa... When Rosa arrives... These both have similar meaning. (For example, if Rosa called and said she is on the way home, so she is coming that day.) Si llega Rosa... If Rosa arrives... (At any moment, maybe today or tomorrow. It does not matter.) 7. Si-Cuando dejas de fumar, estarás mejor de salud. Si dejas de fumar... If you give up on smoking... (There is no hurry. Maybe in years, if that person decides to stop smoking, then he/she will be healthy.) Similar meanings. Cuando dejes de fumar... When you give up on smoking... (If you tells him/her to give up on smoking now, he will be healthy from that moment.) 8. Si-Cuando llama por teléfono Enrique, dile que estoy enfermo. Si llama por teléfono... If he calls... (No rush. At any day, any hour.) Cuando llame por teléfono... When he calls... (In this moment, if he calls.) Like the previous examples. 9. Si-Cuando estés enfermo ve a ver al Dr. Martínez. Cuando estés... When you're ill... (Maybe you're not ill right now, but in the future. In case you're ill...) Si estás enfermo... If you're ill... (There is a possibility that you are sick now, so go to the doctor. If you feel bad or something.) 10. Si-Cuando venga tu padre iremos a ver a los abuelos. Cuando venga tu padre... When your father arrives... (For example, he called and said 'I'm coming'.) Si tu padre viene... If your father arrives... (No rush again. Your father may arrive today, tomorrow or in a couple of years. It doesn't mind. When he arrives, you all will go to...) They both have similar meanings.

1. Si-Cuando acabe este curso, buscaré trabajo en una agencia de viajes. 'Si' is wrong here. When this school year ends, I will... You could say: Si acaba este curso, buscaré... But it has not much sense, because nothing lasts forever. 2. Cuando-Si no llueve, saldremos a dar un paseo. They both have different meanings. Si no llueve, saldremos.... If it doesn't rain, we'll... (Now, if it happens now.) With 'Cuando', it should be: Cuando no llueva, saldremos... When it doesn't rain... (It's raining, so we'll go out later.) 3. Si-Cuando tiempo, ve a comprar la fruta. I don't know what you mean with this. Is it 'Cuando tengas tiempo, ve a comprar fruta'? When you have time... Si tienes tiempo, ve a comprar fruta. They both mean more or less the same. With 'cuando' it is like you say to someone to buy fruits if he/she has a free moment, but using 'si', it's for example when he/she has just finished his/her work and can go and buy fruits. I hope I explained myself right. 4. Si-Cuando vuelva a casa voy a darme una buena ducha. Cuando vuelva a casa... is correct. When I go back home, I'll... (for example, after work) Si vuelvo a casa, voy a darme una buena ducha. If I go back home... (The person doesn't know if he/she will go back that day or not.) 5. Cuando-Si estás cansado, acuéstate un rato. Si estás cansado... If you're tired... (now, in the moment the person is telling another this.) Cuando estés cansado... When you're tired... (If a person is working and his/her mum tells him/her to sleep if he/she feels tiredness. But this person maybe is not tired at the moment his/her mum tells him/her to take a nap in case he/she is.)

I'm not sure how much this helps but si literally means if and cuando means when (as a question and not a question). Sometimes like in English they can be used interchangeably but I'm not a native.