From the wiki provided by those 2 projects, I found it seems they did the similar job. But there must be some difference or it's no need for 2.
So what are the differences, and what is the practical advice to choose from one another.
thx a lot!
Great answers above.
Just quick update with Cloudera+Hortonworks merge last year. These companies have decided to standardize on Ranger. CDH5 and CDH6 will still use Sentry until CDH product line retires in ~2-3 years. Ranger will be used for Cloudera+Hortonworks' combined "Unity" platform / CDP product.
Cloudera were saying to us that Ranger is a more "mature" product. Since Unity hasn't released yet (as of May 2019), something may come up in the future, but that's the current direction. (Oct 2019 update: Unity is now known as CDP and is available for beta testing; will be available for cloud deployments soon, and in 2020 for on-prem customers)
If you're a former Cloudera customer / or CDH user, you would still have to use Apache Sentry. There is a significant overlap between Sentry and Ranger, but if you start fresh, definitely look at Ranger.