In the previous versions of Exchange (Exchange 2010) and Exchange online (Office 365) previous service version , the term litigation hold is introduced

Litigation Hold , is to allow you to immutably preserve mailbox content to meet long term preservation and eDiscovery requirements. When a mailbox is placed on Litigation Hold, mailbox content is preserved indefinitely.

In the new version of Exchange (Exchange 2013) and Exchange online (Office 365) existing service version , a new term has been released which is In Place Hold

In Place Hold, is called query-based and time-based In-Place Hold for the mailbox

After the release of Exchange 2013 and the new Exchange Online, there were some documentation that mentioned that Litigation Hold was being deprecated , this is not true and both terms are available 

Both types are available for use and you should use the hold feature that best meets your needs.  Here are some scenarios to help you choose between the two holds.

Source : TechNet Blogs