Heya.
Here on this forum and many others.. we are all quite lazy.
So we type P for precision and J for Jazz.. Everyone here knows what they mean, so its accepted.. almost part of the Forum slang if you will.
As for the price difference you see among different basses.. If you check the Fender website (Invalid Link Removed) you will see that the
American Series & Highway Series are made in America
Standard And Deluxe Series are made in Mexico
Squires are made in Korea.
Some basses and guitars are made in Japan as well.
Due to the cost of construction, labour, quality control and parts these basses differ in price from country to country and you will see that some basses will outwiegh another.
For example An American Fender is supposed to be the Top of theyre line up.. where as the Squire sits at the bottom.
I hope this helps somewhat