Do junior officers only salute senior officers and admirals and do senior officers only salute admirals?

This sounds strangely like does a 2LT salute a 1LT

When I was in the Navy, junior officers (Ensign) always saluted everyone higher of his rank...period.

Sir, in the Navy we have "JOPA". In normal Navy circumstances O1 to O3 do not salute one another, unless there are junior enlisted present. It's similar to how we use our naming conventions, with O1 to O3 being on first name basis (when not around enlisted) and customs/courtesies being extended to Senior Officers. That said, though in the Navy O4 is still a JO, we don't really categorize them as "true JOs". It's fun to tease them about, but they are no longer "one of us".

Other branches normally extend customs and courtesies up and down regardless. The Navy is unique in our traditions. However, should you cross paths with a member of another force, expect to salute someone of a higher rank.

Everyone, regardless of enlisted/officer rank, is required to salute a MOH awardee...otherwise follow normal military regulations unless in a hostile
fire zone...the enemy loves to "take out" senior officers" first

I would say yes