A relation is someone of your immediate family like brother, sister aunt, uncle or someone like that. A Relationship is between two people, countries basicly between two parties. It can be personal or business related. That is the the difference between these two words and also it is how you place the words in a sentence which can also alter their meaning too.

Hi Tim i'll give you two sentences: that bears no RELATION  to the problem. here another one, they broke off RELATIONS with one another. As for relationship: to have a good RELATIONSHIP with us or  they have an harmonious RELATIONSHIP. iT COULD BE VERY SIMILAR AS STATED BY cbell BUT THE DIFFERENDCE CAN ONLY IMPLIES TO WHAT ARE YOU TALKING 'BOUT  hopefuly is of any help!!!

To my understanding, relation and relationship are very similar. A Relation is when two things share a connection or similarity. This could mean anything from grass to tables to chemistry, where relationship is generally meant as a connection between people. So you and your parents share a relationship. Does this make sense?