In the mainland of China ,we always use simplified Chinese.But in Hongkong and Taiwan ,people always use traditional Chinese.Simplified Chinese is more easy to write than traditional Chinese,and is more widely than traditional Chinese.Do you understand?

Simplified => China (Mainland) Traditional => HongKong and Taiwan

用法，習慣，學習難易度，上手所需時間，學習方式都會有所不同，你想問的是哪方面的不同呢？

before 1949, all of chinese use traditional chinese. after 1949, the leaders of china think the traditional chinese is really hard for foreigner. for example, 臺(traditional) vs 台(simplified). So some chinese experts of language created the simplified according to the traditional chinese. go to search “五四运动” on google, the chinese leader believed simplifying chinese is a continuance of “五四运动” at that time, chinese even tryed some extreame way: using pinyin it means we stop using character, and we use pinyin to replace character. so the chinese became like this: ni hao, qing wen ni jiao shen me ming zi. but chinese realized that using pin yin made us lose the culture in language, so we reuse character and we use pin yin to help pronounce character. some people in Taiwan think simplifying chinese lost the chinese culture. but if you know the evolution of chinese character, i believe u wont be agree with them.

simplified:中国 traditional: 中國