Further to Dan's comments below.
Sometimes 'border' is used to mean the outer edge or boundary of something e.g. a design on a sheet of paper - the border is the edge surrounding what is written or printed. The border of a country may also be its outer edge or boundary. When you arrive in the UK you see a sign which tells you that you are at the 'UK border' although you are not just leaving another country - you left it some time ago and it is a distance away.
'Confine' usually refers to being restricted by space whereas, as Dan says, 'limit' is more general.
'Sunscreen' contains ingredients which prevent u-v radiation from reaching the skin ; sun cream may also contain these, but not necessarily, and may be just an ointment for rehydration.