Imperfecto and indefinido

Question

I've read so many times about the difference between these tenses but It's like banging my head against a wall. "el taxi LLEGÓ veinte minutos tarde y el taxista ERA muy antipático. The taxi driver was unfriendly in the imperfect tense in the same taxi that arrived late in the preterite tense. This is so difficult.

Accepted Answer

It is difficult but it does get easier with practice.
El taxista ERA muy antipático - This is a description of something we view as continuing at the time referred to. There is no beginning or end to the driver's unfriendliness. In fact, we don't care about that as we are just describing what he was like at that time - imperfecto.
El taxi LLEGÓ veinte minutos tarde - This is a one off completed action that happened in the past - indefinido