To get has multiple meanings and uses and is explained here: http://esl.about.com/od/vocabularyreference/a/Uses-Of-Get.htm

They are different verbs with different meanings. To have - is like avoir in French and is used to indicate possession such as "I have a car"; it can also be used as a way of expressing and obligation - I have to go to school each day or I have to study longer - this is like devoir in French. It is also used as an auxiliary verb to form the past and pluperfect of verbs - I have read this book before; I had seen this film when I was a child. To have is not used in English where French would use it to express age "j'ai 40 ans; Here we say "I am 40" using the verb to be.

"I have something" means you currently own or possess a thing. "I got something" is either a very slang way of saying the former, or is used properly and means that you received something. "I've got something" or "I have got something" is just another way of saying "I have something." Also, generally we don't "employ" words so much as we "use" them.