I have seen these words Aupaire, au pair even Opare are they the same? and what is a demi aupair ?

The correct word is Au Pair from the French meaning on par or the same level and is
a person who works for a family (cleaning and/or teaching the children) in exchange
for room, board and pocket money.

Aupair or Au-pair is also correct but Aupaire and Opare would be typos or just
a misspelling.

Aupair usually work 25-30 hours per week ( In Europe ), in the USA it is 40
hours per week. A demi aupair is someone who work for just a few hours per week
possible in exchange for room and board only, the term is seldom used these days.

Of course an aupair+ or plus is an aupair who will work long hours for more pocket
money.