illustrator got vector graphic.
Text that done in illustrator when you go to printing it will be sharp and nice. no matter how much you enlarge it.

photoshop for bitmap graphic.
Text that is done in photoshop can be sharp but only with enuf resolution when it goes to printing. when you enlarge it and the resolution is not big enuf you will start to see that the text is pixelated.

just an example.
so a combination of this 2 kind of software makes good and perfectt designs.

learn photoshop from internet tutorial. no need to go out and pay ppl unless you think that you really dun understand a word about it from the tutorial on the internet