in my mind i'm thinking attached garage is the garage attached to the house and detached garage is a garage that is separate from the house but l saw some houses where the realtors put the garage as detached but it is totally attached and part of the house. so what is the real meaning?

if a door that opens from the inside of the house opens directly into the garage it is attached. some may look like the structure is attached, but you have to go outside the house to go in the garage door..there is no common entry.

If you can get from the garage to the house without going outside, it is attached. Otherwise, it is detached.