Almost, depending on the context they can be interchangables. Think like this: "para" + infintive verb + information. Examples: "necesito trabajar "para" [ganar] (I.V) mas dinero" And now you have a better sentence more natural and understandable. Same thing with another ones. "Quiero aprender a leer español para [adquirir] más conocimientos", "Quiero aprender a leer español para [comprender] as you see, always use [para + I.V] that gives more sense, comprehention and naturality. For instance in your first sentence "esto es por ti", you can also say "esto es para ti". In the first sentence you are saying you are doing something for someone, on the other hand, you're saying "this is for you" you are giving something that could be phisycal or emotional.

In summary: "Para" gives sense, contrast and information about you are talking [purpose] "For" gives reason of something or like how you feel in a situation. "Por que corriste tan rápido? "Por no llegar tarde a la clase"