In LINQ, `IEnumerable` and `IQueryable` are used for evaluating queries against a specific *database* or *collection*. `IQueryable` implements `IEnumerable`.

# `IEnumerable`

1. **`IEnumerable`** resides in `System.Collections`.

2. It retrieves data from a data source, loads it on the client-server, and then filters it.

3. It is more suitable for collections like arrays, lists, etc.  

4. It supports deferred executions; i.e., unnecessary query executions are avoided.


# `IQueryable`

1. **`IQueryable`** resides in `System.Linq`.

2. It retrieves the data from a data source on the client-server after filtering it.

3. It is more suitable for remote data sources.  

4. It supports deferred executions;i.e., unnecessary query executions are avoided.


IEnumerable vs. IQueryable

IEnumerable is best for in-memory collections, while IQueryable is ideal for remote data sources.