I have + (noun)

By using the words 'I have' you are informing someone of something you have possession of or have acquired.
Here are some examples:
"I have a cat."
"I have a nice car."
"I have a house."
"I have a computer."
"I have a headache.

WORDS I'm

I'm

I'm' is an abbreviation for the word 'I AM.'  It is used in 

combination with other words to tell someone about yourself 

or to describe something you are doing.

Here are some examples:

"I'm so tired."

"I'm confused."

"I'm happy."

"I'm twenty three years old."

"I'm hungry."

"I'm nervous."

"I'm excited."

"I'm leaving work."

"I'm thirsty."

"I'm from Seattle."