Full text search or search in a field only

Cany anyoe tell me what is full text search about
and what's the advantage of using it and when you should use it ?

Let say i have table called aritcles with two fields title and body. Title data type is varchar 100 and boday data type is text.

SELECT * FROM articles
     WHERE MATCH (title,body) AGAINST ('$searchword');

And this one

SELECT  *  FROM articles  WHERE body LIKE  '%$searchwords%' or title LIKE '%$searchwords%'

Which method should i use for fast and accurate results ..

Regards