How to Differentiate Teh and Teh C ?

both looks the same to me. We are having lunch at Compass Point today

Colleague A ask : " Teh and Teh C 怎么看？"

Colleague B answers : " 用汤匙scoop , 有糖就是Teh, 有奶就是Teh C "

So colleague A scoop.. and finds neither Sugar nor Milk. :S

Is there really a way to tell the difference between Teh and Teh C without tasting it... Hmmm...