I was reading ASUS’s annual report and I am confused with sales and revenue, can someone please explain to me?

2017 revenue numbers as follows

Taiwan $ 69,893,799 

China 71,942,390

Singapore 174,007,620 

USA 64,473,223 

Europe 28,929,614

Others 24,720,145

Total $ 433,966,791 

2017 Sales numbers as follows

Sales to TW 27,107,279

America 93,752,695

Asia Pacific / Oceania 166,964,495

Europe 143,425,593

Africa 2,716,729

Net sales 433,966,791

What I don’t understand is that why Taiwan‘s revenue number is so much higher than sales whereas Europe’s revenue number is so much lower than sales??  and the overall Sales and revenue number are actually the same??

can someone please explain to me?  Thank you.