I think こちら is more polite way to say これ. We don't use これ for people usually because it sounds rude. It's better to use 彼 or 彼女. こちら is appropriate to use for people and it sounds polite.

They have same meaning but こちら is more polite. Usually japanese people for answering to ありがとう say こちらこそ. こちら here means I and this sentence means It is I who should say so. good luck!

こちら　is a polite one of これ。So, when you buy things in expensive stores The shop staff will say こちらになります。meaning this is . We dont use こちらfor introducing our own family members to others or own company staff to other companies staff. Because we must be humble about ourselves. こちら　is a polite word. When I introduce my younger brother pointing his picture I would say これは、弟です。never say こちらは、弟です。 When we introduce one of our friends to other friends, to use こちらは　or not to use it is a little confusing. So, we just say oooさんです。

This = これ (for an object / = pronoun) - This way is usually, but not always, used as a subject. E.g., This is a pen. This (こちら） is usually not used to refer to objects. You can use こちら as a formal way to refer to a person. E.g., This is Mr. Kobayashi. こちらは小林さんです。