The account that shows up with the dark 'g' icon is your primary sync account. Naturally this should be the same as your primary email account. This is because the phone now uses a Gmail account to sync and backup contacts, emails etc, and it needs to know which account will be that default. Although it uses the email account, it is NOT the actual email account that you would log in to send and receive email, that, as you have already ascertained, is the red gmail icon accounts.
The Droid 4 has two ways of viewing Gmail accounts email. The icons look slightly different, i.e. slightly different variations of the red and white Gmail envelope icon. One is the Motorola Gmail and the other is Gmail's own Gmail app (yes, confusing and a little redundant but they do run slightly differently and look slightly different, particularly in the message list).
Motorola's version has a white envelope with a red '@' symbol letter inside.
Gmail's is the traditional red 'M' symbol letter inside a white envelope.
For Motorola's app, to swap between accounts all you do is press on the envelope logo in the top left of your screen and choose which account
For Gmail's app, to swap between accounts all you do is press on the email address in the top right corner of your screen.
Good luck
NiteCloak