 <p>The way the HTML the generated is different than just a different container. It also gives you some convenience default settings etc.I'd say it would be good if you have to group fields rather than arbitrary components. To quote ExtJS documentation:</p> <p>"A container for grouping sets of fields, rendered as a HTML fieldset element. The title config will be rendered as the fieldset's legend.</p> <p>While FieldSets commonly contain simple groups of fields, they are general Containers and may therefore contain any type of components in their items, including other nested containers. The default layout for the FieldSet's items is 'anchor', but it can be configured to use any other layout type.</p> <p>FieldSets may also be collapsed if configured to do so; this can be done in two ways:</p> <p>Set the collapsible config to true; this will result in a collapse button being rendered next to the legend title, or: Set the checkboxToggle config to true; this is similar to using collapsible but renders a checkbox in place of the toggle button. The fieldset will be expanded when the checkbox is checked and collapsed when it is unchecked. The checkbox will also be included in the form submit parameters using the checkboxName as its parameter name."</p>