as it was explained already: kaszubski (language) and Kaszubi (Poland). Kaszubski is considered a separate language (west-Slavonic group) rather than dialect, while góralski (spoken by highlanders on the south of Poland) is clearly a dialect of Polish.
Kaszubski is very different, a Polish speaker would not understand a word of it. Also writing system is slightly different - we use special diacritics, because there is more vowels in kaszubski than in Polish. For example: Polish Kaszuby (the name of the region) is spelled Kaszëbë :)

There are plenty of interesting internet resources, most of them however is in Polish or in 'kaszubski' (or bi-lingual).
Some good websites: http://www.kaszuby.pl/ (there is a map, so you can see exactly where in Poland it is);
http://www.kaszuby.3miasto.pl/ this one is a big portal, includes some literature (in kaszubski), national anthem, dictionary, etc.

And here are some English resources : http://www.kaszubi.pl/ang/grabowska.pdf (bits of history)

http://syrenadancers.com/kaszuby.html (folk art, etc.)
HTH
Magda - proud Mermaid from Kaszuby :) Hope some ProZ Góral will explain better about góralski :)))