How does phone texting differ from IM or FB messaging?

I lately see a lot of hype on texting. I have a regular phone (not smart) but am thinking of aquiring one, but am not too sure it will benefit me that much.
I am on vacations now till march so have plenty of time to use my PC. Most of my work I do at home also. Can't I use my PC for the same purposes as any smartphone? How does it differ from fb messaging for instance?
Do you think it is that necessary and important/critical to get a smartphone, considering especially that I want to hook up with younger girls??

hmm, you can text using all old phones so no i dont think you need smartphones.. well yeah you can use your pc to chat / flirt / get num / dates etc.. but when the number is gtten, usually the text phase begins..