Isn't soundproofing the same?

It's about absorbing the waves and not letting them bounce/echo/vibrate, etc..

The confusion is the term used.

You must think soundproof is only for not letting sound go out.... u referring to door only?

But it's actually could mean doing up the whole room so that it's absorbing sounds 'inside' the room, so that it doesn't escape out the room from all 4 walls, ceiling and floor.

If going to sound studio, cinema, etc..... you would notice dead silence inside, which in turns means no loud noise heard from outside or neighbouring hall/studio/room as well.

So, theoretically .... soundproofing = acoustic treatment. Unless of course, you are saying acoustic treatment does more than just absorb .... it enhances?