Please don't ever write "coz" or "plz". These are slangy text-speak forms, and not acceptable in regular English.

Just write normally (because, please) and you'll have no problems. That's exactly what native speakers do.

"Cos" and "plz" are known as "text-speak", which means people use them in text messages. They're far less common than English learners seem to think. "Text-speak" is mainly only used by children, even in text messages. Unfortunately lots of learners read that they're informal, and think they're English sound (well, look) more natural if they use them.

The truth is, using "cos" (or "coz" or "cuz"), "plz", "u", "r" etc. are far more commonly used by non-native English speakers than native speakers. Whenever you see anyone using any of these, it's a dead giveaway that the person who wrote it isn't a native speaker.

The same meaning.

they mean the same thing. Coz and plz are just quicker to type, so you'll see them online a lot. you'll also see "cuz" and "cause" from time to time

"Because and Please" are Formal and are used more commonly as our friend above said, is the grammatical most correctly way to use dayle and write and good observed by English Spoken Polite people. By the other hand, "Coz, cuz, pls, plz" people transformed  Talking words used daily and simple reduced the words as more easy talking quickly or writting. One Example of it isthat we find this in musics, chat rooms by internet, etc.