Perhaps this will help: Not all email is created equal: an introduction to POP3, IMAP4 and MAPI | mail2web.com Blog
(More links are at the bottom of that page.)
Just because you change the method of access doesn't change the location of emails which are on the server of the email service providers (the server names on the account tab of the properties for each email account). If you have been keeping work and personal email separate, they were separate because the email service providers are different. For example, it's possibe for someone to have 10 separate email accounts with 10 different email service providers located in 10 different states or countries. That person would then install 10 accounts in their one Outlook program, or if they have 2 devices, then install the accounts on either or both devices. Just be careful to use the appropriate type of service (pop3, smtp, imap, or mapi) depending on the features you want for each account.