I am new to this and need a few things cleared for me. What's the difference between a query letter and a synopsis and if they are different, how long should a synopsis be and what all should it entail?
At the top of the Query letter Hell subforum in Share Your Work there are sticky threads on queries and on synopses. Check them out for in depth answers to these questions.
But in short, the query letter is 350-400 words maximum, and is intended to hook the agent's interest in reading more. There are variations in form and structure, but it is at its miost basic a letter asking the agent if they would like to read more of your book - it must include your contact info, the title, wordcount and genre of the book you are querying, and a brief pitch of the primary plot. It is succinct and usually doesn't outline the entire plot.
A synopsis can be of varying length and does include the entire story from beginning to end, including the end. Depending on length is how much detail you include regarding each plot point and subplot point.
Almost all agents will want a query, only some will want a synopsis. And many will never ask for a synopsis prior to representation. having said that, I drafted a 1 page, 2 page and 5 page synopsis for my book, so that depending one what the agent asked for, i'd have something ready.
Go check out the sticky threads in QLH.
~suki