No such animal as Yahoo Hotmail.. what you are interested in is the differences between Yahoo Mail and Microsoft Hotmail. They are both web browser based email clients. Yahoo lets you store more data (messages) but other than that there really is no difference. Googles Gmail gives you the most space and it can be accessed both via the web and via pop3 (downloaded to your computer) without cost to you.. Hotmail and Yahoo offer pop access for a fee.