as / like - a preposition

1a. It’s almost like a real garden, but it’s actually artificial.
1b. It’s almost as a real garden, but it’s actually artificial.
2a. I worked like a waiter.
2b. He worked as a waiter.
Please correct the above.
Thanks.

This is another of those examples where you’ve asked very similar questions previously and don’t appear to have taken on board what you were told by various people at that time.
As explained previously:
1a is okay, but not 1b.
2a and 2b are both okay but have different meanings.