What is the difference between hashing or encryption a data

1) please some one tell me difference between hashing or encryption a data.

2) i saw hashing also encrypt data which is not human readable and encryption does the same then why people think hashing is different from encryption ?

3) what hashing does ?

4) if we encrypt data then we can decrypt it too but if we hashing the data then can we reverse the process ?

5) if no then what algorithm hashing use that no one can reverse the data ?

6) give me two sample code to has data one will hash data without salt key and another one hash data with salt key.

thanks