juniorLINQ
Difference between IEnumerable and IQueryable
Updated May 16, 2026
Short answer
IEnumerable works in-memory; IQueryable builds expression trees for remote execution like databases.
Deep explanation
IEnumerable executes queries in application memory, while IQueryable translates queries into provider-specific commands (e.g., SQL). This impacts performance and data transfer.
Real-world example
Filtering data in EF Core before fetching from database.
Common mistakes
- Calling ToList() too early causing unnecessary data loading.
Follow-up questions
- When does IQueryable execute?
- Can IQueryable improve performance?