difference between properties and tags in the upper right corner

Question

I dont get the difference between the actual property, enabling the respective funtionality and the tag on the right upper side?

*** Number 5                                         :B_example:
:PROPERTIES:
:BEAMER_env: example
:END:

5 can only be divided evenly by 1 or 5, so it is a prime number.

Can someone explain that to me?

Answer 1

See the footnote in the Frames and Blocks in Beamer section of the Org mode manual:

(1) If ‘BEAMER_ENV’ is set, Org export adds ‘B_environment’ tag to make it visible. The tag serves as a visual aid and has no semantic relevance.