It sounds like your bird experience is very limited. If that is the case, I would guard against getting a rescue bird. I will only recommend rescue birds for experienced bird handlers because most come with bagage in the way of issues that you will have to deal with. If you get your bird from a reputable breeder, they will usually help you out for the first few months with answers to questions. The bird will most likely be more socialized than a bird located in a rescue center or shelter.
Now as far as the differences between a Grey and a Macaw are HUGE, no pun intended, but size, cage size, NOISE level and knowing how to deal with a Macaw. Macaws have attitudes that most other birds don't have. They are BIG, INTIMIDATING and they know it and will use it quite often. So if you are a tad faint of heart when dealing with a large bird, I wouls shy away from a Macaw until you get more experience dealing with birds.
Which ever species you get, at some point you will have to show them whose boss and yep, this can and most likely get you biten. But you will have to do this to maintain control over your bird or they will wind up controlling YOU.
Now as far as the differences between a Grey and a Macaw are HUGE, no pun intended, but size, cage size, NOISE level and knowing how to deal with a Macaw. Macaws have attitudes that most other birds don't have. They are BIG, INTIMIDATING and they know it and will use it quite often. So if you are a tad faint of heart when dealing with a large bird, I wouls shy away from a Macaw until you get more experience dealing with birds.
Which ever species you get, at some point you will have to show them whose boss and yep, this can and most likely get you biten. But you will have to do this to maintain control over your bird or they will wind up controlling YOU.