Cleansing is more intense with Water Fasting compared to juice fasting. My 3-day Water Fast was more intense than my 10-day master cleanse. My 10-day Water Fast was very different than my 10-day juice fast. I'm not saying juice fasts are bad, they just cleanse more slowly (which isn't always bad). Also, some people find them easier.
I've never gone past 10 days, so you're in unknown territory for me. I personally will never fast that long.