How can the Zen school of thought distinguished from the Chan school of thought? Both spring from Mahayana, true; but what are the basic differences?
Both originate from Bodhidharma, the first patriarch of Zen and Chan, as he transferred Indian heritage up north. The difference is that Zen was technically Chan that was imported to Japan by the likes of Dogen Zenji, and because both languages are different, here you go - different word. It is respectively Thiền in Vietnam, and Seon in Korea, all of which refer to the same thing. On the other hand, Chan is more rooted into Chinese philosophy, you could find traces of Taoism and Confucianism there, mostly unlike Zen.
Having said all of the above, Zen is very minimal, Soto Zen for that matter deprioritises chanting and koans and focus on zazen almost entirely. They meditate with their eyes open staring at the wall, posture is very important, due to how Japanese society is disciplined you might even get hit with a stick by your master if your posture is off. The key is in Zazen, it is in between of Samatha and Vipassana in my opinion. Zazen is almost entirely associated with enlightenment, as Dōgen said that practise itself is Enlightenment.
Rinzai school for another example has strong rooting in Japan but not entirely (it’s derived from Chinese Linji) and they, on the other hand utilise koans to cut through rational, dualistic thinking to make leaps in experiencing enlightenment.
All of the rest is standard Mahayana approach: Bodhicitta, Bodhisattva vow. There is some Amidaba Buddha influence regionally, which is Pure landish, but not omnipresent. Also, Zen/Chan (etc) stresses Yogacara school philosophy that is mind only school.
I generally recommend a classic book on Zen by Philip Kapleau - The Three Pillars of Zen if you are interested in Zen.
The Nikujiku Saitai may have had some effect. This Meiji edict legalized meat and marriage for monastics, which caused quite a stir in the Japanese Zen community and had lasting repercussions. In Japan, some monks maintain the celibacy precept. Others do not. The Japanese culture has assimilated the effects over time, but for travelers unfamiliar with the edict and its repercussions, it can be quite a surprise.