I hope these two examples are useful for you: POR "He never told her BECAUSE he was afraid of losing her" "He apologized FOR lying" PARA "This is FOR you" "I studied a lot TO pass the exam".

There are not just one or two differences. They are used in many different ways and in specific situations.

"Por" indicates the agent in passive sentences "El caballo es comprado por Juan." It also denotes the cause "cerrado por vacaciones" the mode "Por las buenas." the price "comprado por tres monedas." the multiplication "Cinco por cinco" "Para" denotes the end or term to which an action is directed. to indicate the place or time to be deferred or determined to execute something or finish it "Pagará para mañana"

POR is used to answer the question why. And PARA is to reflect the objective of an action or to indicate the possessive.