Hamsters and rats are very different species, and so require very different things from their owners.
First and foremost, rats need to be kept in pairs or groups, rather than singly like most hamsters. Keeping a rat on it’s own is likely to lead to a very upset pet. Lots of hamsters need to be kept on their own as they’re quite territorial, but rats need a friend to keep them company.
Some hamsters will need to be kept on their own
Second, rats need a very large home so that they don’t fight amongst themselves. In general, rats are a lot larger than hamsters and therefore need a lot more space. If they are kept in conditions that are too cramped, it is inevitable that fights will break out.
Rats are far larger than hamsters, and always need to be in pairs or groups. Do you have enough room for two rats? The general advice is that each rat will need about two cubic feet of space at the very least. So, for two rats, you’ll need at least a cage with four cubic feet of space, and the more space you can give them the better.
Rats are larger than even the biggest hamster species
Some owners claim that rats are more affectionate than hamsters, but this is likely to vary on a pet-by-pet basis. Rats can be extremely affectionate pets, bonding strongly with their owners and actively seeking their affection. Rats are extremely intelligent creatures and they can make very entertaining pets.