Difference between mastic and sealant

[Bek2017]

Total plumbing-tiling novice.

Our bathroom has been tiled. What should we use where the walls meet and where the tiles meet the ceiling - mastic, sealant or caulk? I'm confused about the difference and have had varying advice.

Once it's sealed, can I cover the edges (ceiling, floor, wall to wall) with edging, or is that not a 'done' thing?

Thanks

 

[ShaunCorbs]

Silicon in the corners and around the tray / bath and to the ceiling nothing as it should be upto it

 

[Bek2017]

Silicon in the corners and around the tray / bath and to the ceiling nothing as it should be upto it

Thanks. There is a gap at the ceiling unfortunately.

 

[ShaunCorbs]

Thanks. There is a gap at the ceiling unfortunately.

How much of a gap ?