While every product has one general ProductName, it can have different titles that are used while publishing the product to marketplaces like eBay. The keywords used in the title have a big impact a listing's visibility and having multiple titles can multiply the product's chances of being seen and ultimately purchased.
A title needs to be approved before it will be used for eBay. This is a precaution to prevent someone from using the wrong title accidentally.
These are the different types of titles:
RegularTitle - not assigned to any of the other types
ShortTitle - used for websites, when they have an abbreviated title that displays on search results or while advertising related products.
SubTitle - used optionally for eBay listings. Enable client setting Enable Sub title for eBay Listings to post the sub-title to eBay.
TopTitle - the main title