Briefly, difference between aroma oil diffuser and Chakoro is the temperature. Chakoro is higher.
Generally, the fragrance may be weaker than aroma diffuser but the safety might be better. You don't have to worry about chemicals in aroma oil. If you could make a good adjustment Chakoro may use as a aroma oil burner. But don't forget you must be careful, the candle is burning!
To burn green tea may be the standard but some tea leaves, coffee and herbs seems to be popular these days.
Below stylish Chakoro are available to buy direct from Japan through Rakuten Global and amazon.co.jp. If you have an interest to buy, refer "How to use Rakuten Global" or "How to buy on amazon.co.jp" But maybe you don't need to, because it's easy.