Which Boeshield T-9 is for my bike chain and which one is ment for anti-corrosion?
Boeshield T-9 is one product with the same benefits.
So all different packaging variants can be used for waterproof lubrication and for corrosion protection (also salt water)

Can Boeshield T-9 be used to protect metal against salted roads during winter?
Use T-9 to protect the inside of your metal bike frame, chain, spokenipples, electronic connections etc during winter.
Re apply each month or every second month (depending on the weather conditions) or after washing your bike.

Can i use T-9 on the outside of my (sail) boat engine to protect it against salt water corrosion?
Since T-9 is flammable, won’t it burn when the engine becomes hot?

The gas inside the aerosol is indeed very flammable. But as soon as the solvents dissolves and T-9 dries out to a coating, this isn’t flammable.
So NEVER use T-9 on a running engine or when the engine is still hot!
Leave on for a couple of hours before turning it on again.