There is a core misconception in regards to Bushido and samurai. The term Bushido was made popular by Inazo Nitobe in his book Bushido: The Soul of Japan from 1899*.* In the book he makes the comparison by the supposed "Bushido code" and European chivalry. AFAIK he believed he made up the term himself, but earliest known use of the word occurred some time during the 1700s. From peacetime started in Japan from the early 1600s to mid-1800s, a lot of samurai were philosophizing and debating the role of samurai in peace time. Inazo based his argument on these discussions as well as his own opinions. It is generally seen as fairly fictitious and not representing samurai warfare and culture, and there simply was no "bushido code". Japan really consisted of many smaller nations up until 1868 (although controlled by a central union government from 1600), so there was many local cultures rather than one all-encompassing one.

If we look back to pre-Edo samurai, we'd find that their concept of honor is very different from modern-day western concepts of honor. Idk how comparable it was to European knights, so I'll leave that to someone else. It's first and foremost important to realize that samurai have about 800 years of legacy, and their culture and definitions of honor varied from time period to time period. What Inazo wrote about was closer to what he thought samurai honor was all about.

If I were to try and mention some core concepts of samurai honor, what their heroic tales depict as the great warriors, it's often based on fearlessness, winning, and loyalty to one's superior. This doesn't mean loyalty was always the trend, because we find periods where supplanting your lord was common (gekokujo). However, everyone loves loyalty, especially those in power, so loyalty and self-sacrifice was praised and rewarded. Winning over your enemy and being and remaining powerful could also result in others ignoring certain acts which could be seen as dishonorable.

When it came to combat, fearlessness and defeating the enemy were the essential concepts of honor. If you killed your enemy while he was sleeping or otherwise unaware, it was considered to be his slip up, rather than you fighting dirty. Being killed due to your own inattentiveness would be considered your own weakness and as being un-warrior-like. However, being killed while bravely facing unsurmountable force was admired, as well as bravely dashing towards the enemy (as long as you killed several of them). Many legends are described dying while fighting bravely to secure the retreat of their lord or something similar. Scoring the first, second, or third kill of a battle was also great.

Many doubt that the samurai were truly as fearless as myths describe. Personally, I think they are fairly accurate. The reason is that the Europeans who came to Japan during the Azuchi-Momoyama period and early Edo period wrote in amazement about the sheer glee and eagerness samurai expressed when facing death. It could be a problem for lords and generals, as you don't want your warriors to seek death needlessly. So it was therefore considered "a dog's death" to die without achieving great service to your lord. Basically, your death should achieve something. This is contrary to the assertion that Bushido says a samurai should aim at dying. The war-time samurai avoided death until a heroic death was the best outcome. Sources even advice warriors to look out for someone who dressed for death rather than fighting and winning, and reporting them.

Inazo also mentions honesty, constancy, humanity, and justice as parts of the "Bushido code". However, his pre-Edo predecessors were not really any of those. Justice was really might makes right. Honesty was not important either, as a large part of warfare was using counter-intelligence. During the Siege of Osaka, Tokugawa Ieyasu lied to the Toyotomi, making a fake peace agreement in order to justify removing parts of the castle's outer wall and building a ramp, before he attacked the castle and killed everyone. Constancy, was not really important, as samurai at war were very pragmatic. One lord would support another up until it became inconvenient, and could turn around and attack his ally. Such were the case of The Battle of Sekigahara, when Kobayakawa Hideaki's army changed side, and this wasn't uncommon at all. Humanity is probably the last I'd call samurai. Killing infants and children, and burning entire civilian villages was not even frowned upon if it served some purpose, politically or tactically. One famous event was the Battle of Dan no ura, where the Minamoto army chased down the child emperor, resulting in his death. Others are the burning of Enryakuji and Ishiyama Honganji, where Oda Nobunaga's armies burned every single warrior, monk, civilian, and child in entire temple towns.

A good, quick and easy read on this topic is Bushido or Bull? by Karl Friday. Oleg Benesch also wrote a book on this called Inventing the Way of the Samurai.