Slang is kind of difficult to explain properly. The words it encompasses are constantly changing and being added so instead of trying to address every slang word it is easier to say what slang is not so that you are able to differentiate between what is slang and what is not.
Slang is large category which encompasses lots of words. There are however many other words that are often mistaken as words which fall under the category of slang. Some examples of this are jargon, cant, regional dialects, slogans ect. Though these types of speaking may sound similar to slang they have their differences. With out having grown up with a specific type of slang it will be hard to get a hang of it and if slang is used incorrectly, it will seem strange and out-of-place among natives. In order to fully blend in, one must know what type of words and phrases they should not use.
With all the different types of speaking, it’s easy to get them mixed up. It’s important to know the major differences so that you don’t get mixed up and you know what kinds of words you should and shouldn’t say in the various situations.
It is possible for other words to be added to slang, but for the most part, the other categories listed are completely separate form of slang.
Below are the different types of speech not included as slang:
The Slang Site 