InMemory tables :
1. Holds data temporarily in client or server tier
2. These tables can't be stored in Database
3. Can't apply security
4. We cannot use InMemory table buffers
5. InMemory temporary table is used when the data set is small
TempDB tables :
1. Holds data temporarily in database till the scope is valid
2. These tables are stored in the database
3. Can apply security
4. TempDB table buffer can be used in coding
5. TempDB is normally used for larger datasets to improve performance