Both are so much related to each other. And both are so dissimilar! What are the differences between friendship and love? Is platonic friendship possible between persons of opposite sex? Let us try and understand.
What is friendship? Why do we call a person our friend? When do we call someone a very good friend? If we care for a person, if we are always ready to help that person and if we share most of our thoughts with a person, they are our good friends. We can always count upon our good friends in an emergency. We are always sure that our friend will understand why we acted in a certain way. We need not explain anything to our very good friends. The friendship is so deep and the relationship is so intimate, that most of the things are automatically understood by our friends.
What about love? In a relationship of deep love, all the sharing that we discussed above are taken for granted. But love transcends all this. During love, we are attached with a particular person, while in friendship, one may have many friends. A loving relationship makes one so much attached to the other, that one gets pained if his/her beloved is hurt! Love also involves a physical element. Friendship does not have that. This is a vital difference. Nature gives us love so that the specie can go forward. Nature does not give us friendship.