I came across couple of questions in exam dumps of 70 - 667 but bit confused if someone can explain me difference between output cache and object cache in few lines and possible scenarios we use them in please.
What Object cache does is stores metadata about SharePoint Server objects (like SPWeb, SPSite, SPList, etc.) on the WFEs. When a page is rendered, if there is data that needs to be retrieved through these objects, the SQL Server will not be hit. Features of SharePoint that uses Object cache are publishing, content query web part, navigation, search query box and metadata navigation. There are only few things you can do about this type of cache - set size.
Object cache is something what is done automatically. You have to handle content cache manually.
Object cache - metadata, WP queries of external sources, search boxes, quick launch, breadcrumb
Default is on
Configurable through GUI or web.config per each SC
BLOB cache - binary large objects like images or CSS files, stored on WFE disks
Default is off
Configurable through GUI or web.config
Page (output) cache - for whole pages to load them faster for next user with the same rights
Default (for publishing pages) is on
Configurable through GUI (page atributes) or web.config
Office web app cache - XAML queries, images inside documents and so on
Default is on
Configurable through PowerSell, has its own SC (one per web app)
... luccio is right, I just like images :o)