What is the difference between a poolish and a sourdough starter?
The main difference is the word "sourdough" which implies using a sourdough culture as opposed to baker's yeast. Right or wrong, the words "poolish," "starter," "preferment," etc. often get used interchangeably. You can read the definitions in the glossary for more insight.
Can i grow my own starter?
Yes, between this message board and the search feature at the top of the page, you should be able to find many sets of instructions on how to do so. I'd also suggest reading through the posts here to get some background knowledge on sourdough cultures, starters/preferments, etc. Lots of good info here. Also look in the message boards for the styles that interest you. Particularly in the NY and Neapolitan forums you will find a lot of good information about baking pizza with preferments.