You can check local book store or dealer sometime you can get discount
on the software but if you are taking it in school you can also try the IT
service, most of university or college offers education version of the
software if it is part of the requirement.
Photoshop creates pixel file, it is mainly use to fix or manipulate the photos,
it is also capable to create some photorealistic image from scratch. The file is
extremely large, and if the resolution is not high enough, the image will
became pixilated
unlike photoshop, illustrator creates vector files, images create in this
program will not lost its resolution no matters how big you expand it. I think
the names of these programs are pretty straight forward, illustrator is mainly
used to generate graphic and if you have these two program you’ll find they
work like charms, there is no hassle between importing and exporting, you simply
just need to drag over the image from one to another.
For example if you are doing fashion design, you can draw your sketch in Illustrator
than find the pictures with desire fabric than do the colour change in photoshop and
past it on your design.