Ombré: 

Ombre hair design is completely darker roots, blended into existing colour of mid lengths and ends to create “the rooty look.” 

Balayage:

Balayage means to "Ramdomly"sweep or paint hair colour directly onto the hair, mainly at the ends to mid length...
 It is done in sweeping teqhniques to lighten the ends of your hair.
If you’re thinking of going lighter then this look allows you to try it out.
It’s a colour technique people love because it grows out gracefully.