What are the differences between Iqueriable and IEnumerable?

 IEnumerable are found in a System.Collections Namespace while the IQueryable are found in a System.Linq Namespace.

If you are use IEnumerable when querying data from in-memory collections like List,

Array collection etc And when querying data from out-memory (like remote database, service) collections so you are use IQueryable.

Because While querying data from database, IEnumerable execute select query on server side,load data in-memory on client side and then filter data.

Hence does more work and becomes slow. While querying data from database,

IQueryable execute select query on server side with all filters. Hence does less work and becomes fast.

 

for more details check this  link

http://www.c-sharpcorner.com/UploadFile/a20beb/ienumerable-vs-iqueryable-in-linq/