Nautilus is the default file manager coming with GNOME, the popular desktop environment shipped by default in distributions like Ubuntu, Fedora or Debian. Nautilus has a clean and easy to use interface, and its functionality can be expanded using scripts. It features tabs, three view modes (icon view, list view and compact view), the possibility to sort items by name, size, type, modification date or even emblems (a feature specific to Nautilus), bookmarks, file previews, possibility to browse the network, and media devices support. However, the media support will only detect GNOME players like Rhythmbox or Totem, so you will also need to have those installed in order to use it.
Dolphin is now the default file manager in KDE4, and it definitely does a good job for an application which was designed with simplicity and usability in mind. It supports tabs, service menus, sorting by many rules, including permissions, ownership or modification date; it provides a modern KDE4 interface with the possibility to preview images, video files or documents; it supports splitting tabs vertically and browse the network. A few days ago I put up a full Dolphin review here, and I must say I was really impressed by this nice file manager.
Rest at http://tuxarena.blogspot.com