This is a very short blog to simplify and to show the main differences of what you may have heard the structured and the unstructured data. If you are a developer then you have certainly worked before with SQL Server or my SQL, creating tables, relations, columns, rows, queries and so on for a basic target is to have a well-structured database where you can easily manage your data, get reports, insert, delete and do all necessary main functions.
On the other hand, in your application you certainly have to work with other type of data, like videos, pictures and files, where you can only post them online but you cannot do to it the same things you do your database or your unstructured data. You cannot insert into the file, you cannot write queries to get few words or lines from specified file.
For sure the data types for the databases are changing from time to time, I mean you can insert now images and some unstructured data into it however can you still make analysis on the unstructured data you insert into your database? I am sure that each type of data has its own specific time to use, there is no specific type of data is preferred on the other one, it all depends on your needs and the cost.