Why is Spanish Choral Music in the Renaissance different from Italian Choral Music?

I’m doing an essay on this and I dont know where to get started. I’d appreciate if anyone just laid down the basics, suggested some pieces of music and/or composers, or helped out in any way.
The essay is supposed to be around 10,000 words so really anything helps. Thanks!
Also- if choral music is too specific, i’m considering narrowing down the topic to just music in general. Thanks!

Are you sure they were so different?

I have chosen a known Spanish and Italian composer.

1- Spain: Cristóbal de Morales
Biography:

http://en.wikipedia.org/wiki/Crist%C3%B3bal_de_Morales

A piece by him so that you can listen to it:

http://www.youtube.com/watch?v=R6nJ6jiT3eQ

2- Italy: Giovanni Pierluigi da Palestrina
Biograhy:

http://en.wikipedia.org/wiki/Giovanni_Pierluigi_da_Palestrina

To listen:

http://www.youtube.com/watch?v=VhpQgOpFEsY

http://en.wikipedia.org/wiki/Giovanni_Pierluigi_da_Palestrina