Eu tive is more precise, like, Ontem eu tive um sonho (Yesterday I had a dream). Eu tinha is related to a continuous action, like, Quando eu morava com os meus pais eu tinha um cachorro (When I lived with my parents, I had a dog). You had it for a period. Whereas (tive) is more like "one time" or once.

TIVE é um passado recente que tem de certa forma alguma ligação com o Presente, seria o nosso present perfect, algo como have had. TINHA é o passado distante que não tem mais ligação com o presente, seria o past em si, algo como had apenas.

Eu tive means that you had to do something but right now you don't have to do it anymore because you have already done. So, for example: "Eu tive que pagar as contas, eu tive que te falar" (I had to pay the bills, I had to tell you because it was hurting me) you totally did it. Eu tinha means that you had to do something, but it doesn't mean that you did. For example: "Eu tinha que te falar (not an obligation), Eu tinha que ter ido na casa dela (it doesn't mean you went to her house).

sempre, quando eu tinha 20 anos , I mean, when you want to talk about your age in past, you used tinha , tive is not used for age .....but you can say : eu tive um acidente de carro esta manhã