Athough they look very different, there are relatively few differences between domestic cats and tigers. They are 99% the same in terms of anatomy and behaviour. The default position is to regard them as fundamentally the same, although of course they are a different species of cat.
Although this difference goes without saying, I will state the obvious that tigers are up to 100 times heavier than domestic cats.
Tigers have one type of coat which is an orange background with high contrast dark brown or black stripes of which there are about a hundred on each tiger. Each tiger has their own individual style of stripes and they can be identified by them. Domestic cats are seen in a very wide range of coat types although the original domestic cat was a tabby-coated North African wild cat. At the beginning of cat domestication there was only one coat on a domestic cat and that was the tabby coat but now there is an infinite variety due to the evolution of the domestic cat over about 10,000 years.
Eyes – pupil
Although the fundamental structure of the eyes of both the tiger and domestic cat are identical, the tiger has a round pupil while the domestic cat has a slit for a pupil.
Tigers have one colour of eye which is hazel or copper whereas domestic cats have a wide range of eye colours once again due to 10,000 years of evolution as domestic cats.
The domestic cat is well known for their “tail-up” greeting (a friendly greeting). Tigers don’t do this. Their tails are held horizontally or tucked between their legs.
Through selective breeding of purebred cats the ear size in a percentage of domestic cats varies tremendously whereas tigers all have the same shape of ear which is quite small and rounded relative to head size.
We know that the domestic cat cannot roar while the tiger can. The tiger does not purr like the domestic cat. In fact, the tiger has quite a wide range of sounds that domestic cats do not make. But tigers do meow, spit, growl and hiss just like domestic cats.
In general, domestic cats are not that fond of being in water e.g. swimming in water. This is in complete contrast to tigers who like to be in water. The can spend a long time in water cooling off and staying cool in their hot climate. They are excellent swimmers and can swim in the sea for several miles.
Tigers live in the wild although of course you will see them in zoos i.e. in a captive state. They belong in the wild while domestic cats belong in the home and are fully domesticated normally or they should be. Domestic cats are socialised to people whereas nearly all tigers are not which means domestic cats get on with people and tigers don’t. Although you will see celebrities sometimes having tigers as pets but this is not to be recommended. And captive tigers are to a limited extent socialised to people but even then they can attack and kill people.
Although there are an estimated half a billion (500,000,000) domestic and feral cats on the planet, the tiger population has been rapidly diminishing over the preceding hundred years by various human processes such as hunting, poaching, loss of habitat and loss of prey which has left them with a tiny population of about 3,500 across the entire planet. The difference is staggering in this aspect.
As mentioned, the domestic cat and the tiger have, at heart, exactly the same behaviour. The domestic cat’s behaviour is modified by their socialisation to humans and living in the human home where they have to interact with people which modifies the behaviour. But if a domestic cat goes outside on their own and wanders around a large backyard or garden or in a forest they become little tigers behaving almost identically to their large, wild cousins although the hunting style of domestic cats and tigers varies somewhat.