Difference between IEnumerable and IQueryable in C#

In C#, we have often used collections Interfaces IEnumerable, and IQueryable interchangeably, but it’s very important to know the difference between each other. Each interface has its own specific characteristics, that differentiate them and which make it more adaptable to certain scenarios.

Let’s explore the difference between IEnumerable, and IQueryable in C# and which interface to use in which case, let’s see.

Here are the differences between IEnumerable and IQuerable:

• IEnumerable is an interface in the System. Collections namespace, whereas IQueryable is an interface in the System.Linq namespace.
• IEnumerable is used for in-memory collection queries, whereas IQueryable is suitable for querying data from out-of-memory collections, such as remote databases or services.
• IEnumerable is beneficial for LINQ to Object, while IQueryable is beneficial for LINQ to SQL.
• Both support deferred execution, but IEnumerable does not support lazy loading, whereas IQueryable supports lazy loading.
• IEnumerable doesn’t support custom queries, while IQueryable supports custom queries using CreateQuery and executes methods.
• IEnumerable does not run filters on the server side. While IQueryable executes a “select query” on the server side with all filters. When querying data from a database.
• Both can only move forward over a collection.
• The IQueryable interface inherits from IEnumerable, so it can prefer everything that IEnumerable can do.

Summarizes the key differences between IEnumerable and IQueryable:

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