what is the difference between the von baeyer test and the bromination of hydrocarbons?

Question

I guess they both test for the presence of double bonds and triple bonds. I wonder what more they could offer.

Answer 1

Yes, they both test for the presence of double and triple bonds.
The von baeyer test uses a alkaline potassium permanganate solution which is purplish-pink in colour. If it reacts with a double or triple bonded hydrocarbon, the solution will turn brown.
The bromination of hydrocarbons means that bromine solution is added to the hydrocarbon. Bromine is brown in colour. If bromine is reacted with a double or triple bonded hydrocarbon, the solution will turn clear.

Of course, if a baeyer or bromine solution is added to a single carbon bonded hydrocarbon, the solution will not change colour.