in / at

[English4everyone]

What is the difference between in and at? I have seen both of these sentences. Are they different?
1. He is in the pool.
2. He is at the pool.
or
in the restaurant
at the restaurant
Is there any rule to learn the difference?

[Barb_D]

What is the difference between in and at? I have seen both of these sentences. Are they different?
1. He is in the pool. He is in the water.
2. He is at the pool. He is in the area surrounding the pool or in the water itself.
or
in the restaurant. He is inside the building
at the restaurant. He is in the area surrounding the restaurant (the parking lot, the sidewalk outside) or inside the building.
Is there any rule to learn the difference?

At is less specific than in in these cases.