Can anyone tell me what the various icons to the left of folders in the
navigation pane mean?

I have just converted my pst file to 2003 format, and now I have two
apparently identical sets of "personal folders" being displayed. The icon
by one of them has a little hosue and maybe a clock(?), and by the other
one is what looks like a set of folders.

The two sets of folders display identical sets of data.

Whats going on?