Hi John,

兒童節快樂！

The differences are not big really.

Tone-wise, native Guangzhou accent has 7 tones including the high falling while HK accent merges it into high flat. Vocab-wise, HK speech has more English words.

Here's an episode of my favorite Guangzhou soap/sit-com 外地媳婦本地郎(roughly translated as Non-local wives and Local Husbands), a very popular TV series in GD. It's mainly in Guangzhou Cantonese but you'll also hear Mandarin or Shandong-ese or even English spoken by some of the wives from outside Guangdong. Perhaps you could check it out and hear the differences yourself.

http://v.youku.com/v_show/id_XNDUzOTk5Ng==.html

Hope it helps. Let me know if you've got more questions.