I keep hearing this question, so I thought I’d attempt to offer some brief insight:
Applications are platform-specific. (facebook or myspace). Widgets can function on any site that accepts external content. This includes social networks, blog platforms, start pages, desktop platforms personal web sites –
Widgets can function differently on different platforms. So for example a widget may not fully integrate with a specific social network, or deliver varying degrees of integration with a social network like accessing an using certain social data. The benefits of Widgets are that they encourage connectivity, self-expression or collaboration think – GAMES – TOOLS – INTERACTIVE CONTENT
Applications tap into sharing and data via a social network like facebook or myspace via friends, locations etc.