Take my words with a grain of salt. I am mostly writing metaphors here.
Quick intro to BFS and DFS
In Graph Theory, we perform a search by traversing the graph. We start with one node and traverse the entire graph until we find what we are looking for.
In BFS, we search all the neighbour nodes first. And then search the 2nd-degree neighbours, then 3rd-degree, and so on. Here is a neat animation from Wikipedia for you.
But in DFS, we start with a neighbour and keep going in its branch as deep as we can, and then backtrack to a second neighbour and go deep into its branch, and so on.
What are you saying?
BFS and DFS can be seen among people as traits of how they make friends. Like introversion and extroversion, BFS and DFS are the characteristics of people's approach to friendship.
You might already have some idea by now. Take few seconds and draw a picture. Imagine two people (one doing BFS and other doing DFS) and think how they are different. It is fun to observe and ponder. :)
College campus life is a perfect setting to spot both kinds of people.
How are they different?
A person who is on the extreme end with BFS would generally have a larger number of friends and smaller number of acquaintances. They constantly seek to convert their acquaintances into friends. They do not have any hard time making friends with someone. They have a fear of missing out on creating new friendships as time slips by.
A person who is on the other extreme with DFS would have a significant number of acquaintances but a smaller number of friends. They would always be interested in taking their friendships on to the next level. They are NOT afraid of missing out on new friendships and want to work a lot on the existing ones.
BFS people can generate the same intensity in new friendships, as with their existing friends. They don't need much time for this. Yet, most of the time BFS people are afraid to go deep into conversations with one friend. They would stop at one point. They would fall out of conversations pretty easily. They wouldn't be interested in knowing more about their friends. They would be certain they know enough about them.
DFS people never get bored with the friends they hangout with. They are willing to share deepest level of spiritual secrets with each other. It takes a significant amount of time for their newer friendships to reach the intensity of their existing friendships. They have strong perceptions, but loosely-held. They would cheer to look at things from other people's perceptions.
Let me know if you can think of more differences.
Everyone has to do BFS first. In first year of college, you don't have enough nodes to do DFS with. So, you spend the first (and maybe second) year doing BFS. You join clubs, you hangout with your hostel-mates, and neighbours to create threads.
After this, if you are a DFS person, your DFS mode will trigger. And it never stops.
I do not have a dichotomous view on which is the right way of living. I believe one has to find the right balance.
Thanks to Nishant Nikhil for bringing this up, one fine evening back in college.