The line-height is different inside RadPanelBar because the normal items are vertically centered and vertical-align: middle works only when line-height is set. On the other hand RadFormDecorator doesn't change the styling of elements which have a set class name, so RadPanelBar wins.
About the padding and margins - A RadPanelBar sub-item has spacing in front of it so the hierarchy can be easily seen, however this shouldn't apply to templates, can you send a live URL so we are able to check why this happens? Thank you in advance.
All the best,
the Telerik team
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