Spanish POR v PARA

Por- Cause / Motive

Por- Movement

Por- Transportation / Communication

Por- General Location 

Por- General Time / Duration  

Por- Ratio / Proportion

Por- Price / Exchange

Por- Agent of action (author, singer, etc)

Para- Purpose of

Para- Express Opinion

Para- Destination

Para- Deadline / Future Date

Para- Intended Recipient

Para- Comparison with the norm  

Para- Employment