[Alext180]

What separates Cohesion and Adhesion? Every definition I see says Cohesion is similar molecules sticking to one another, and adhesion dissimilar things sticking to eachother. But what constitutes "similar" and "dissimilar"? The polarities of the molecules? Or the actual kind of molecule?

[DrCMS]

Think about this example you glue your hand to a car. 
How well the glue sticks to your hand and how well the glue sticks to the car is adhesion.
How well the glue bonds to itself is cohesion.

If someone now drives off in the car and the glue peels off from the car or from your hand that is an adhesive failure but if the glue stays stuck to your hand and to the car but snaps in between that is a cohesive failure. 

If you use supper glue and the car drives off taking the skin off your hand then the glue had greater adhesive and cohesive strength than your hand.

[Alext180]

That's a good example... So water sticking to "other polar molecules" would be cohesion? or Adhesion?