Difference between Lamda expression and LINQ query

Each style has their pros and cons. Query syntax is nicer when it comes to joins and it has the useful letkeyword that makes creating temporary variables inside a query easy.

Fluent syntax on the other hand has a lot more methods and operations that aren't exposed through the query syntax. Also since they are just extension methods you can write your own.

I have found that every time I start writing a LINQ statement using the query syntax I end up having to put it in parenthesis and fall back to using fluent LINQ extension methods. Query syntax just doesn't have enough features to use by itself.

There are some LINQ extension methods which do not have counterparts in LINQ query expressions, and will require the use of Lambda Expressions. A good example is Enumerable.ToLookup - if you want to create an ILookup, you need to use lambdas to generate this