Branching descent :
Different species descending from the common ancestor - get adapted in different habitats.
e.g., Darwins finches - varieties of finches arose from grain eaters/Australian marsupials-evolved from common marsupial.
Natural selection :
A process in which heritable variations enable better survival of a species to reproduce in large number.
e.g. White moth surviving before the industrial revolution and black moth surviving after industrial revolution/ Long necked giraffe survived/DDT resistant mosquito survive.