RELATIONS 和 RELATIONSHIP在表示两者（人 ,国家 ,ETC）关系这个意思上面,如果没有什么感情的意思是可以混用的.比如中美关系,两者都可以
和FRIEND,FRIENDSHIP；MEMBER,MEMBERSHIP的关系类似,但要复杂一点,主要原因是在于RELATION本来就是抽象的东西.FRIENDSHIP可以看成FRIEND之间的一种关系.RELATIONSHIP也可以看成RELATION的关系,就是关系的关系.
比如：
THE RELATIONSHIP BETWEEN ME AND MY FATHER,我和父亲的父子关系上的感情层面的关系,可以用好或者不好来形容
THE RELATION BETWEEN ME AND THIS MAN IS SON AND FATHER.表示一种客观存在的联系,就是父子联系.就没有好和不好的概念,因为它是客观存在的关系.
因此,RELATIONSHIP可以带有感情的意思,比如用来指一段恋情.
relation
1.A logical or natural association between two or more things; relevance of one to another; connection:"the relation between smoking and heart disease"
2.The connection of people by blood or marriage; kinship.
3.A person connected to another by blood or marriage; a relative.
4.The way in which one person or thing is connected with another:"the relation of parent to child"
5.relations
a.The mutual dealings or connections of persons,groups,or nations in social,business,or diplomatic matters:"international relations"
b.Sexual intercourse.
6.Reference; regard:"in relation to your inquiry"
relationship
1.The condition or fact of being related; connection or association.
2.Connection by blood or marriage; kinship.
3.A particular type of connection existing between people related to or having dealings with each other:"He has a close relationship with his classmates".
4.A romantic or sexual involvement.
relation
KK:[]
DJ:[]
n.
1.关系,关联[U][(+between/to)]
Their relation seemed quite close.
他们的关系似乎十分密切.
2.(国家,团体,人等之间的)关系,往来[P][(+between/with)]
They are anxious to develop friendly relations with their neighboring countries.
他们急于同邻国发展友好关系.
3.血缘关系,亲戚关系[U][(+to)]
4.亲戚,亲属[C][(+of)]
He had no other near relations.
他没有其他近亲.
5.【婉】肉体关系[P][(+with)]
6.【律】(导致起诉的)告发[U][(+of)]
7.叙述[U][(+of)]
His relation of his adventure fascinated us.
他讲述的关于自己的冒险经历使我们听入了迷.
8.叙述的事,故事[C]
relationship
KK:[]
DJ:[]
n.
1.关系,关联;人际关系[U][C][(+between/to/with)]
The children learned about the relationship between the moon and the tides.
孩子们弄懂了月球与潮汐的关系.
2.亲属关系;姻亲关系[U][(+to)] :3.风流韵事;恋爱关系[C]
What is your relationship to the victim?
你是受害者的什么人?
