rarely invisible=visible??

Question

Is it the same?
Another question,Pigeons can carry messages for four years.=
If goes well, their(pigeons) flying career lasts about four years.??

Answer 1

rarely invisible=visible
Are almost the same except rarely means it still can occur but not like or often, so invisibility still can occur
where as visible means it's able to see all the time


and the pidgeon one
the top one says they can carry a message for up to four years
and the bottom one says that their career can last up to four years so they're different

Answer 2

I would say rarely invisible=usually visible.

For the pigeon one, the second is one possible interpretation of the first, but it should say "if ALL goes well". The first one isn't really clear, so it doesn't necessarily mean the same as the second (it actually suggests that the poor pigeons would be flying around with the same message for four years).