Thanks for the response! Yeah agree.... I think I am beginning to work it out... My language (Swedish) actually translate the words differently. I primarily use English dictionaries so I hadn't checked it.
However, in English both words are "bed".
The word for "постель" is more to do with bedding.. and lying in bed... and кровать is the actual bed.
лежить в постели (lie in bed)
купить кровать (buy a bed)
But it's still not completely clear. I liked your example sentences!