Philosophical and Doctrinal Differences between Theravada and Zen, and its effects The difference between Theravada and Zen may be like night and day. I favour Zen over Chinese Mahayana because I don't quite prefer the Pure Land beliefs. Hence, I want to compare these two.

I already know that in Theravada, one seeks Nirvana and it is sufficient to become a Arahant which is already difficult enough to attain. However, in Mahayana, one aspires to go in the path of the Bodhisattva. 

However, philosophically and doctrinally, what are the major differences between Theravada and Zen? Please elaborate.

For e.g. Zen has Buddha Nature and Emptiness which do not feature in Theravada. Compassion also features more strongly in Zen than Theravada. Zen also has Absolute Truth vs. Relative Truth? On the other hand, Theravada strongly emphasizes the Four Noble Truths, Three Marks of Existence, dependent origination and the Noble Eightfold Path. I'm not sure how important these Theravada doctrines are to the Zen tradition.

How do these differences in philosophy shape the differences in mindset and world views between the two?

For example, are Zen Buddhists more compassionate towards the suffering of others, while Theravadins are more detached from, and thus more apathetic towards the suffering of others?

Another example: Are Zen Buddhists more in touch with their emotions in terms of compassion and appreciation of the Buddha Nature and Emptiness in nature and in the world around them, compared to Theravadins who may want to be detached from their emotions?

The philosophical and doctrinal differences may also influence differences in terms of practice. Any examples of this?
The difference is an entirely different canon!  Theravada follows the Pali canon whereas Zen pulls most of its philosophical underpinnings from the Mahayana sutras and its own oral and written traditions (i.e. koan collections, writings of folks like Dogen and Hakuin, etc.).  That being said, I don't know how you would begin to explore what the effect on mindset would be.  I would also wonder if it even makes sense to make that investigation.  So much depends on the practitioner and their own development along the path.  I've known practitioners of Zen who were total, intellectualizing jerks and Theravadans who were oceans of compassion.

Outside of the obvious doctrinal differences, another rather ironic difference between the two camps is the practice of meditation.  Jhanas, as described by the Buddha in the Pali canon, don't often make an appearance in Zen.  I say ironic as the word Zen itself is a twice removed transliteration of the word jhana (i.e. jhana/dhyana -> ch'an -> zen).  In practice, Zen does not emphasize or pay much attention to being in, say, the third jhana over the second.    

I'm a little taken aback by your statement that Theravada Buddhism doesn't emphasize compassion to the degree Zen does.  If anything, the opposite is true.  You find all sorts of meditations on the cultivation of compassion and loving-kindness in the elder tradition (the Brahmaviharas for instance) whereas Zen doesn't take the same practical, directed approach to its development as found in the Pali canon.

Lasty, emptiness does factor into Theravada.  See the Maha and cula sunnata sutta for just two, albeit less emphatic, explorations of emptiness. 

And to reemphasize, so much of this depends on the practitioner.  I don't think it's helpful to view either school as monolithic.  Setting one against the other isn't necessarily helpful or, in my opinion, even possible.