Difference between HasOne and BelongsTo in Sequelize ORM

Question

I am developing a sails.js app with sequelize ORM. I am a little confused as to when BelongsTo and HasOne need to be used.

The documentation states that :

Answer 1

This is more universal problem.

The main difference is in semantic. you have to decide what is the relationship (Some silly example):

Man has only one right arm. Right arm belongs to one man.

Saying it inversely looks a little weird:

Right arm has a man. A man belongs to right arm.

You can have man without right arm. But alone right arm is useless.

In sequelize if RightArm and Man are models, it may looks like:

Man.hasOne(RightArm);      // ManId in RigthArm
RightArm.belongsTo(Man);   // ManId in RigthArm

And as you notice there is also difference in db table structure:

BelongsTo will add the foreignKey on the source where hasOne will add on the target (Sequelize creates new column 'ManId' in table 'RightArm' , but doesn't create 'RightArmId' column in 'Man' table).

I don't see any more differences.