I often wondered, WHAT is the difference between washi and masking tape. I own a small collection and not all are the same, so I assumed some were washi and the others masking tape. So I thought I'd google it and I found this answer over at Kado Cato:
"There is no difference, it's exactly the same. Originally it launched on the market as Japanese masking tape. At one point 'washi tape' became the accepted international term. In Japan it is known as masking tape and the most famous brand of washi tape is simply called mt (which stands for masking tape). The term 'washi tape' refers to the fact that the tapes are made of Japanese rice paper." Thank you Cato for clearing this up for me. I guess the tape is like any other product, there's always some variation.
It was brought to my attention that this is not completely correct: All washi tape is masking tape, but not all masking tape is washi tape, they're not ALL made from ricepaper. Thanks Rivka de Jonge for sharing!
Rivka had some other read material-tips about the tapes, here's a blogpost from She Knows Living and a Wikipedia article. Thanks!
Masking tape from Een Nieuw Avontuur