> If you bought unlimited ticket

And that's the difference. IIRC, you have to periodically top up your Suica card with money which then gets deducted from the balance each time you use it.

In Europe, there is no such thing - sure, you can buy a lot of single ride tickets and then use them when you need to, but you have to stamp the ticket when you start each ride, which does seem a little more inconvenient.