You call them sanctions when you talk about your enemies, you call them tariffs when you do it to your friends. The difference is nearly 0.

Sanctions involve a total ban on trade. tariffs involve a tax on imports, quota impose a limit on imports. If only 0 was an asymptote it would fit your description.

Think of ban as a variable between 0 - 1. Sanctions = 1.0 and Tarrifs < 1.0. Tarrifs are sanctions.

(Increasing taxes on something is a partial ban).

Singapore doesn't. Not in the trade protectionist sense anyway.

Not really, even Singapore has its duties. It's only 0% for everything if you're going for re-export.

https://www.customs.gov.sg/businesses/valuation-duties-taxes...

Excise is a bit different to tariffs though. Even if you produced those items in Singapore you pay the same excise.

The 20% on cars isn't to protect the (non-existent) car manufacturing industry of Singapore, but to reduce demand for cars.