Difference between internal and external testers in iTunes Testflight beta testing?

Question

Can anyone please explain in complete details the difference between internal and external testers in iTunes Connect Testflight beta testing? The difference here is just too

Answer 1

Internal Testester

1. Email id should be used with apple account
2. Internal tester will be a member of developer account. Roles may be Admin, Technical, Manager, Developer, Marketer
3. Only 25 internal testers are allowed
4. Each tester can test on upto 30 devices
5. Can test 100 apps at a time
6. Build remains active for 90 days
7. No app beta review

External Tester

1. Email id need not to be used with apple account
2. 10,000 external testers are allowed
3. Can test 100 apps at a time
4. Build remains active for 90 days
5. App required beta review.