CSS Templates allows you to structure your document according to HTML standards without compromising the look-and-feel of the page. CSS designers now can create attractive pages with much grace and style, while adhering to principal code validation.
HTML 5 Templates
The most up-to-date web standard for HTML. Many new features are available with the additional markup tags. More structured and easier to use templates.
Responsive Web Templates
Responsive Web Design are sites which are coded to deliver the correct size screen view no matter the device. Use to provide great looking and readable sites on iPad, iPhone, Androids devices as well as laptops and desktops.
Bootstrap contains coding for device responsive sizing. Sites will display a specific layout rule-set for Laptop, Desktop, Tablet and smartphones. This will help ensure your sites are "usable" especially on smaller size devices.