While at 6.1 there was both a web and two desktop clients (GTK - 'official', Koo - 'community') at version 7.0 there is only a web client, as neither the GTK client or the Koo client are work and both will not be developed further.

The main difference at 6.1 with GTK was the ability to update multiple records and click buttons on multiple records - although the multiple record update is available with version 7 in a community module.

Module at - http://bazaar.launchpad.net/~server-env-tools-core-editors/server-env-tools/7.0/files/head:/mass_editing/

As with most client options, some people prefer one over the other. Most of our clients perceive the web client as being easier for 'regular' users, even more so now at version 7.0.

Hi Vivekrajan,

Apart from the above answer, I would like to say that both have advantages over another. Based on experience in OpenERP, users used to desktop client. In desktop client there are shortcut to do some tasks whereas in webclient there aren't any. One of the other advantage of desktop client is speed. But by look & some nice graphics webclient is best. You can achieve a great look & presentation in webclient.