What's the difference between hashing and One way encryption?

I suppose that the term "one way encryption" gets back to the days when no cryptographic hash function was available, so to get a password hash on Unix systems for instance an encryption function was used (DES). However, instead to provide a fixed key to encrypt the password (normal usage of this algorithm but which would allow to decrypt the password using this same key), the password itself was used both as the key and as the data to encrypt.

By this way, a one way encryption was achieved since there was no way to decrypt the password without already knowing it. Afterward, time went on, a lot of people including highly qualified mathematicians and high-profile security engineers worked on the subject, and provided us better tools for each needs (here: password hashing functions). Nowadays no one should therefore try to tinker with existing algorithms to use them in an inappropriate way (an encryption is used to encrypt text, and not to produce a hash).