Alexa ranks websites based on estimated page views and unique visitors. The higher the traffic estimates, the higher the Alexa Rank of a website. Alexa takes these estimates and provides a list of websites from most popular to least. The rank is from one (most popular) to one million (after which Alexa stops ranking the websites).
Majestic Trust Flow can apply to websites or particular web pages. It is a score based on quality of links. Quality is measured based on the distance from a set of trusted seed sites. The lowest Trust Flow score is zero. That means a website or page is very distant from any trusted website. The highest Trust Flow value is 100 which means it is very close or frequently linked to from the most trusted websites on the web.