Why does smoked salmon look 'raw'? And why does it taste so different from a cooked fillet?

I don’t tend to eat much fish, but in the supermarket earlier I saw some smoked salmon which didn’t need cooking, and some salmon fillets which did. They looked the same really - both ‘raw’. I decided to buy some of the fillet. It was nice, but a very different flavour from when I’ve tried smoked salmon in the past....