Can someone please explain to me the TCP/IP model?

I am required to write about the OSI model and the TCP/IP model for my coursework. I have finished the section on OSI and am now meant to be writing about TCP/IP. Is TCP/IP just a shortened version of the OSI model, or is it more complicated than that? My plan of attack is to basically say "the TCP/IP model is like a shortened version of the OSI model, except that it has only 4 layers and its less theoretical than the OSI model." But obviously in a lot more words... Is this right or do I need to know more first?