What's the difference between IP Address and ISP host?

[DogFacedBoy]

I changed my registered address a while back and got an alert at the time
It included a line like:
Change of email address was made from:
IP Address:XXXXX
ISP host: YYYYY

Thank you,
ebay

Are we overlooking anything

C'mon geeks, fill me in, I'm still learning.